CN108290370A - Laminated packaging material and the packing container being produced from it - Google Patents

Abstract

The present invention relates to a method of manufacturing a laminated cellulose-based liquid or semi-liquid food packaging material, wherein the laminated packaging material has a body material layer made of paper, cardboard or other cellulose-based material, the innermost heat-resistant An airtight and liquid-tight thermoplastic polymer layer, said innermost polymer layer for direct contact with packaged food, a barrier layer laminate between said body layer and said innermost layer. The invention also relates to a laminated packaging material obtained by this method and a packaging container for liquid food packaging, comprising or made of a laminated packaging material obtained by this method.

Description

Laminated packaging materials and packaging containers made therefrom

technical field

The present invention relates to a laminated liquid or semi-liquid packaging material having a barrier paper layer and to a method for producing the laminated packaging material.

Furthermore, the invention relates to a packaging container comprising or entirely manufactured from a laminated packaging material. In particular, the present invention relates to packaging containers for liquid food packaging comprising laminated packaging material.

Background technique

Single-use disposable type packaging containers for liquid food products are usually produced from paperboard or cardboard based packaging laminates. One such commonly occurring packaging container is the Tetra Brik Sold under the trademark, mainly used for aseptic packaging of liquid food (such as milk, juice, etc.), sold for long-term environmental storage. The packaging material in such known packaging containers is generally a laminate comprising a main layer of paper or cardboard and an outer layer of liquid-impermeable thermoplastic. In order to make packaging containers airtight, in particular oxygen-tight, eg for aseptic packaging and packaging of milk or fruit juices, the laminates in these packaging containers usually comprise at least one additional layer, most commonly aluminum foil.

On the inner side of the laminate, i.e. the side intended to face the filled food contents of the container produced from the laminate, there is an innermost layer applied to the aluminum foil, which innermost layer may consist of one or Constructed of several partial layers, comprising heat-sealable thermoplastic polymers, such as binder polymers and/or polyolefins. Also on the outside of the bulk layer, there is an outermost heat-sealable polymer layer.

Packaging containers are usually produced by means of modern high-speed packaging machines of the type which form, fill and seal packages from packaging material webs or packaging material preforms. Thus, the packaging container can be manufactured by joining the two longitudinal edges of the web to each other in a lap joint by welding together the innermost and outermost heat-sealable thermoplastic polymer layers, the laminated The packaging material web is reformed into tubes. The tube is filled with the intended liquid food product and then divided into individual packages by repeated transverse seals of the tube at a predetermined distance from each other below the level of the content in the tube. The package is separated from the tube by a cut along the transverse seal and formed by folding along crease lines made in the packaging material to obtain the desired geometrical configuration, usually parallelepiped or cube.

The main advantage of this continuous tube form, fill and seal packaging method concept is that the web can be continuously sterilized prior to tube formation, thereby offering the possibility of an aseptic packaging method, ie one in which the to-be-filled Bacteria are reduced in the liquid contents of the packaging as well as in the packaging material itself, and the filled packaging containers are produced under clean conditions, allowing the filled packaging to be stored for long periods of time even at ambient temperatures without microbial growth in the filled product risks of. As mentioned above, Tetra Another important advantage of the compact packaging method is the possibility of continuous high-speed packaging, which has a considerable impact on cost efficiency.

Packaging containers for sensitive liquid food products such as milk or fruit juices can also be produced from sheet blanks or preforms of the laminate packaging material according to the invention. Starting from a tubular blank folded into a flat packaging laminate, the package is first produced by fabricating the blank to form an open tubular container enclosure with one open end closed by folding and heat sealing an integral end panel. The container enclosure thus closed is filled with the food product in question (eg fruit juice) through its open end which is then closed by further folding and heat sealing the corresponding integral end panel. Examples of packaging containers made from sheet and tubular blanks are the traditional so-called gable top packs. There are also packages of this type that have molded tops and/or screw caps made of plastic.

The aluminum foil layer in the packaging laminate provides gas barrier properties considerably superior to most polymeric gas barrier materials. Traditional aluminum foil-based packaging laminates for aseptic packaging of liquid foods are still the most cost-effective packaging materials available on the market today at their performance level.

Any other material that competes with such foil-based materials must be a cost-effective raw material, have comparable food preservation properties, be sufficiently mechanically stable and have comparable ease of conversion into finished packaging laminates .

Further reductions in the cost of today's packaging materials can be achieved by reducing the thickness of the polymer layer or by attempting to replace the aluminum foil barrier layer with one or more different barrier layers, which has proven to be quite a challenge. Another way of saving cost which has heretofore not been considered practical in the field of liquid carton packaging would be to reduce the amount of cellulose based body layer by the type and/or amount of cellulose fibrous material. It often results in compromises of important attributes of mechanical strength and package integrity, as well as material barrier properties, and was previously considered a less favorable way forward. Paperboard is a major part of liquid carton packaging material, but also a major part of the total packaging material cost.

Contents of the invention

Now considering the above, it is an object of the present invention to realize a new method of reducing the cost of laminating cellulose-based liquid or semi-liquid food packaging materials.

It is also a general object of the present invention to provide a cost effective laminated cellulose based packaging material with sufficient mechanical stability and good or even improved barrier and integrity to meet the needs of liquid carton laminated packaging materials.

A particular object of the present invention is to provide a cost-effective laminated cellulose-based packaging material having good mechanical properties, good oxygen barrier properties and improved barrier properties against migrating free fatty acids.

Another object of the present invention is to provide such a laminated packaging material at low cost with an increased material content based on biomaterials and renewable materials, ie from unutilized sources of fossil raw materials.

Yet another object is to provide a laminated cellulose-based packaging material based on a down-gauged body layer or core layer, which has comparable mechanical strength and barrier properties to conventional such packaging laminates, The body itself has reduced mechanical strength, eg lower bending stiffness, compared to conventional liquid packaging board.

A specific object of the present invention is to provide a cost-effective, non-foil, cellulose-based and heat-sealable packaging laminate with optimum compressive strength and flexural stiffness for the manufacture of materials for improved or The purpose of aseptic packaging containers for long-term storage of liquid foods that maintain nutritional quality.

According to the present invention, some or all of these objects are thus achieved by the method for manufacturing laminated packaging material, the packaging material obtained by the method and the packaging container made therefrom, as defined in the appended claims.

Detailed description

For the purposes of the present invention, the term "long-term storage" means that the packaging container should be able to maintain the quality (i.e. nutritional value), hygienic safety and taste of the packaged food under ambient conditions for at least 1 or 2 months, for example at least 3 months, Preferably longer, such as 6 months, such as 12 months or longer.

The term "package integrity" generally refers to package durability, ie resistance to leakage or breakage of the packaging container. A major contribution to this property is the provision of good internal adhesion between adjacent layers of the laminated packaging within the packaging laminate. Another contribution comes from the material's resistance to defects within the layers of material (such as pinholes, cracks, etc.), and another contribution comes from the strength of the sealing joint by which the materials are sealed together when forming the packaging container. With regard to the laminated packaging material itself, integrity properties are therefore mainly focused on the adhesion of the individual laminated layers to their adjacent layers and the quality of the individual material layers.

The term "liquid or semi-liquid food" generally refers to a food product having a runnable content that can optionally accommodate chunks of food. Dairy and milk, soy, rice, grain and seed drinks, fruit juices, nectars, still drinks, energy drinks, sports drinks, coffee or tea drinks, coconut water, tea drinks, wine, soup, jalapeños, tomatoes, sauces (such as pasta sauce), beans, and olive oil are some non-limiting examples of contemplated foods.

The term "sterility" in relation to packaging materials and packaging containers refers to the state in which microorganisms have been removed, inactivated or killed. Examples of microorganisms are bacteria and spores. Aseptic processing is typically used when products are packaged aseptically in packaging containers.

The term "heat sealing" refers to the process of welding one surface of thermoplastic material to another thermoplastic surface. Under appropriate conditions, eg, under conditions of sufficient heat and application of sufficient pressure, the heat-sealable material will be capable of creating a seal when pressed against and in contact with another suitable thermoplastic material. Suitable heating can be achieved by induction heating or ultrasonic heating or other conventional contact or convective heating means such as hot gas.

The term "bulk layer" generally refers to the thickest layer or layer containing the majority of material in a multilayer laminate, i.e., the layer that contributes most to the mechanical properties and dimensional stability of the laminate and the packaging container folded from the laminate layer. In the context of the present invention, it can also mean a layer providing a larger thickness distance in a sandwich structure, which further interacts with a stabilizing facing layer with a higher Young's modulus on each side of the bulk layer, so that Sufficient such mechanical properties and dimensional stability are achieved.

A "spacer layer" is a layer that creates a distance or space between significantly thinner layers of material having a higher Young's modulus and density, such as high density and high tensile disposed on each side of the spacer layer The stiff paper layer or foil or film, ie the layer that provides stiffness and stability, is the so-called facing layer. The spacer layer has a low or reduced inherent bending stiffness and therefore does not directly contribute much to the bending stiffness of the laminated packaging material by itself. Indirectly, however, it may have a very large effect on the bending stiffness of the laminated packaging material through interaction with adjacent or laminated layers on both sides, some of which are in contact with the spacer layer Compared with higher Young's modulus but lower thickness. In sandwich constructions it is important that there is at least one such facing or stiffness enhancing layer on each side of the spacer layer. A facing layer on each side of the spacer layer is required when the spacer layer has a very low density and is not contributed by any bending stiffness properties. The flexural strength and flexural stiffness of the laminated sandwich structures increase as the distance between the paper face layers increases.

The "body layer" may comprise a "spacer layer" and an additional composite layer within the body, but may also be the same as the spacer layer.

According to a first aspect of the present invention there is provided a laminated cellulose based liquid or adhesive food packaging material for heat sealing into aseptic packaging containers comprising: a layer of paper, cardboard or other cellulose based material host material, an innermost The heat-sealable and liquid-tight thermoplastic polymer layer, the innermost polymer layer for direct contact with the packaged food, the barrier layer laminated between the main body layer and the innermost layer for its additional bending stiffness to the laminated packaging material Contributed where the barrier layer is a dense surface barrier paper with a density of 800kg/ ^m3 or more, a surface roughness (smoothness) value of less than 450ml/min (Bendtsen ISO 8791-2), and a thickness of 60μm or less, Gram weight is 60g/m ² or less.

The dense surface barrier paper may have a thickness of 20 to 40 μm and a grammage of 20 to 40 g/m ² , such as 25 to 35 g/m ² , such as 25 to 30 g/m ² .

Additionally, the dense surface barrier paper may have a Bendtsen surface of 300 ml/min Bendtsen or less, such as 250 ml/min Bendtsen or less, eg 200 ml/min Bendtsen or less Roughness value.

The dense surface barrier paper material may have a tensile strength of 40 to 80 MPa, such as 50 to 70 MPa, such as 55 to 65 MPa, in the cross direction (CD) and 140 to 65 MPa in the machine direction (MD). A tensile strength of 180 MPa, such as a tensile strength of 150 to 170 MPa, such as a tensile strength of 155 to 165 MPa. This means that such a dense surface barrier paper can carry about 5 times more force per width than aluminum foil and is therefore ideal for use as a sandwich structure with the required mechanical properties for liquid carton packaging top layer.

Furthermore, the dense surface barrier paper material may have a wet strength (ISO 3781) of 0.4 to 0.6 kN/m. This is an advantage when the paper is to be coated with an aqueous composition such as polyvinyl alcohol, which is then dried to form a smooth and uniform barrier layer, and is therefore not damaged by all the application of the composition's water or out of shape. In addition, good wet strength prevents excessive edge capillary action when laminated packaging materials must pass through humid environments, such as when sterilized in hydrogen peroxide baths, or when exposed to humid or high humidity storage conditions.

Preferably, the dense surface barrier paper material may have an air permeability below 2.0 nm/Pas, such as below 1.8 nm/Pas, such as 1.7 nm/Pas or lower, such as from 0.1 to 1.7 nm/Pas (according to SCAN P26 measurement). This property will be balanced with the grammage of the paper for optimum barrier and coating efficiency. A dense surface is one that is substantially free of porosity, ie the surface is devoid of large pores such that the interface towards the immediately adjacent layer or coating becomes uniform, strong and well defined over the thickness dimension of the laminate. This is also a feature that can well help resist the migration of grease and oils into the paper's cellulose network.

Dense surface barrier paper materials may have a tear resistance (ISO 1974) of less than 200 mN in MD as well as CD. Naturally, tear resistance decreases with decreasing paper thickness, and lower values and thicknesses improve openability of open perforations and cutting/tearing of laminated pre-cut holes, etc.

The dense surface barrier paper may be a so-called greaseproof paper, however it should not be coated with any typical greaseproof coating such as silicone or Teflon. The dense surface of this paper has been provided during the manufacturing process by mechanical working and possibly chemical treatment in order to provide a non-porous surface which is as smooth and closed as possible. Thus, the dense surface paper may have a grease resistance according to Tappi 454 of less than 1200 seconds, such as 100-1000 seconds, such as 200-1000 seconds.

The thermoplastic polymer of the innermost heat-sealable layer may be a polyolefin, such as polyethylene, eg a blend of metallocene catalyzed linear low density polyethylene (m-LLDPE) and low density polyethylene (LDPE). When the innermost polyolefin layer was applied directly to the dense surface barrier paper, a significant increase in the barrier properties of the laminate was seen.

Furthermore, the other side of the dense surface barrier paper may be laminated to the body layer by a tie layer of a thermoplastic polymer such as a polyolefin such as polyethylene such as low density polyethylene (LDPE). In this way, the dense surface barrier paper is encapsulated between the polyolefin layers, so that the oxygen barrier properties of the laminated barrier paper material are further enhanced.

When the dense surface barrier paper is extrusion coated with a thermoplastic polymer melt, the oxygen barrier properties of the barrier paper increase in a more than additive manner, so that the barrier properties obtained are surprisingly good. Even more surprisingly, in complete contrast to the case of pure aluminum foil barriers or metallized layer barriers, it has been seen that the level of oxygen barrier provided in laminates by the barrier paper itself is Laminates which are not damaged after being formed into packages have insufficient mechanical properties if used to directly replace conventional liquid packaging cardboard in one way or another. The low-cost host material may, for example, have one or more reduced mechanical properties, such as, for example, lower bending stiffness in the thickness direction or reduced compressive strength when having a lower density, such that adjacent barrier Layers get less support and stability from the main layer. On the other hand, the bulk layer may also be too rigid and resistant to folding into shape as required by conventional liquid paperboard. Although the oxygen barrier level of the dense surface barrier paper itself may only be sufficient for some products and the limited shelf life of filled packages, these initial barrier properties can still be obtained in small, stable packaging containers. Continues under tension and stress. This suggests that these papers may have a good balance of thickness, density, tensile strength, and surface roughness such that oxygen barrier properties are not only better initially than other high-density papers, but also when laminated into packaging laminates and further Sustained after filling, forming and sealing into a package.

The dense surface barrier paper may further be coated with a vapor deposited barrier coating, such as a metallized coating. Oxygen barrier properties are not further improved by metallized coatings, but light barrier properties are added to the paper, which is a must for many food packaging materials. On the other hand, the oxygen barrier properties of the dense surface barrier paper of the present invention are not deteriorated by the physical metal vapor deposition coating process. Deteriorated oxygen barrier properties have previously been observed when metallizing other similar high grammage high density precoated papers, and in this case it is also expected why the barrier papers of the present invention also exhibit in this respect Remarkable and surprising abilities. Therefore, the metallized dense surface barrier paper of the present invention exhibits oxygen barrier properties and excellent light barrier properties.

In an alternative embodiment, the barrier paper may be coated with a diamond-like carbon coating (DLC) in a plasma enhanced chemical vapor deposition (PECVD) process.

According to another embodiment, the dense surface barrier paper is first coated with a precoat of barrier material and then further coated with a vapor deposited barrier coating on the precoated surface.

The precoat is preferably applied in low quantities by dispersion or solution coating of the barrier polymer composition. The pre-coated barrier material can be selected from polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), starch and starch derivatives, cellulose and cellulose derivatives (such as nano/micro fibrous cellulose and nanocrystalline cellulose) , and other polysaccharides and polysaccharide derivatives, a group consisting of polyvinylidene chloride (PVDC) and polyamides.

Melt extrusion coating of thin precoat layers is also possible, but coating with thin layers of only a few microns is difficult by extrusion coating, and bonding to the paper surface and penetration into the cellulosic fiber network are also difficult. Probably not as good as wet (preferably aqueous) so-called "liquid film coating" with the aforementioned hydrophilic polymers.

In a particular embodiment, the precoated barrier material is a PVOH precoat of about 1 to 3 g/m ² , such as 1 to 2 g/m ² , and the vapor deposited coating has an optical density above 1.5, such as from 1.8 to 3, such as from 2 to 3, such as 2.5 metallized coating. This coating composition has been shown to exhibit very good oxygen barrier properties when laminated to thermoplastic polymers such as polyolefins, e.g. polyethylene, which is also surprising since the same coating composition has not Proven to provide good oxygen barrier use in combination with other thin or similar high density papers. Quite surprisingly, we've actually found a combination of paper substrate and coating that work together in a synergistic fashion to provide oxygen barrier performance on par with aluminum foil and that's on par with today's traditional liquid carton laminates Compared to even laminated packaging materials with less mechanical and dimensional stability, where other degraded barrier properties have been expected. While cracks or defects may appear in the barrier coating of the dense surface barrier paper, a substantial level of oxygen barrier properties may also be maintained in the paper substrate itself. Furthermore, the metallized layer provides a better adhesive interface with the immediately adjacent polymeric laminate layer (eg polyolefin, eg polyethylene) than a PVOH pre-coat. Better adhesion to adjacent laminate layers is also an advantageous property compared to DLC vapor deposited barrier coatings. Lamination of adjacent polyethylene layers to a PVOH surface may require tacky polymers to form a strong bond between the polyethylene and PVOH, but this is where the barrier layer surface is a metallized aluminum layer or a DLC oxygen barrier coating not necessary. When PVOH is laminated directly to polyethylene, it has been seen that the material may delaminate at the transverse seal of the package.

The bulk layer may comprise a layer of low density cellulosic material or a layer of low cost cellulosic material having otherwise insufficient mechanical properties for use as a spacer layer in a sandwich structure within a laminated packaging material, the spacer layer having a density of less than 850 kg /m ³ , eg less than 700 kg/m ³ .

The bulk layer may comprise a spacer layer of cellulose-based Containerboard material, such as a fluting material or a linerboard material.

In a specific embodiment, the spacer layer may be a fiber layer made by foam forming process with a density of 100-600 kg/m ³ , such as 200-500 kg/m ³ , such as 300-400 kg/m ³ .

According to a second aspect of the present invention, there is provided a liquid, semi-liquid or viscous food packaging container comprising the laminated packaging material of the present invention. The packaging container may be made entirely of laminated packaging material by folding a sheet or roll blank into a cuboid or other folded to form package or simply into a pouch package. Alternatively, it can be used as a packaging material sleeve for combination with plastic bottle caps and the like.

According to a third aspect of the present invention there is provided a method for manufacturing a laminated cellulose based liquid or viscous food packaging material comprising the steps of:

a) laminating a dense surface barrier paper to the bulk layer;

b) Applying the innermost heat-sealable thermoplastic polymer layer to the other side of the dense surface barrier paper.

The dense surface barrier paper is bonded to the bulk layer by at least one layer of adhesive polymer or adhesive composition.

Thus, a dense surface barrier paper can be laminated to the bulk layer by melt extrusion lamination with a thermoplastic tie layer.

Alternatively, the dense surface barrier paper can be laminated to the host material layer by applying a small amount of an aqueous adhesive composition and subsequently drying the paper and host layer by laminating the paper and host together without any forced drying. bonded to each other.

The method can have the following additional steps:

c) Applying an additional layer (including a printed base layer) having a printed decorative pattern to the other side of the main body layer.

The printed substrate layer on the outside of the host material layer may be a density higher than 600 kg/m ³ and a grammage of 100 g/m ² or lower, such as 80 g/m ² or lower, such as 70 g/m ² or lower additionally The paper layer, which is used as the facing layer in the sandwich structure, interacts with the spacer layer of the body material layer and the dense surface barrier paper on the opposite side (ie the inner side) of the spacer layer and body material layer.

According to a more specific embodiment, the method may include the following steps:

a) providing a roll of central module body material comprising cellulose spacer layers having low or reduced intrinsic bending stiffness, a density of less than 850 kg/m ³ , such as less than 750 kg/m ³ , in grammage 60-250g/m ² ,

b) providing a web of outer material modules comprising at least a printed substrate layer with or without decoration printed or applied thereto, the outer material modules being for the subject material that side of the packaging container that is made of laminated packaging material will point towards the exterior,

c) laminating the outer side of the web of central module body material and the outer side module web of material to each other,

d) Add decorations to the outside material module,

e) providing a roll of an inner material module comprising at least a dense surface barrier paper as defined in the present invention, the inner material module being for that part of the subject material which is to be directed towards the interior of a packaging container made of laminated packaging material that side,

f) laminating the inner side of said web of said inner module material and said web of said central module body material to each other,

g) applying an outermost transparent and liquid-tight protective layer on the outer side of the outer material module,

h) applying an outermost thermoplastic liquid-tight and heat-sealable layer on the inner side of the inner material module,

i) webs of laminated cellulose-based liquid or viscous food packaging material are thus obtained for further winding onto reels,

wherein the spacer layer constitutes the center of a sandwich structure within the laminated packaging material, said sandwich structure having a dense surface barrier paper arranged as a paper face layer on the inner side of the spacer layer and with an outer side of the spacer layer The paper face layer and the additional face layer have a significantly lower thickness but a higher Young's modulus than the spacer layer.

The method steps may be performed in any order, although the order listed above is considered to be advantageous from a lamination setup point of view. Alternatively, the inner and outer material modules may be prefabricated, ie pre-laminated, so that a lower density and relatively more sensitive center module with a bulk layer comprising or consisting of a spacer layer will only need to withstand two lamination operations. Since the lower density spacer layer is more sensitive to pressure and stress, it may be advantageous to pass it through the laminator station to the finished packaging laminate in as little time as possible. In a particular embodiment, the outer paper face plies should be laminated to the main body ply first so that they can be pre-cut together when prefabricated holes, openings or slots are made in the thicker main body portion of the material, as is done today in Traditional body made on cardboard. Such pre-cut holes or openings or gaps will thus be encapsulated between the laminated layers which are laminated in subsequent operations, comprising inner layers and dense surface barrier paper, and an outermost protective polymeric object layer.

When the laminate has tear perforations or pre-cut straw holes or pre-cut openings in the body layer, by having such packaging laminates have a dense surface barrier paper on the inside of the body layer, the pre-cut holes There are particular advantages with regard to the improved openability of laminated films composed of further layers in the region. The opening device or straw typically has a cutting or slitting feature such that when the cap or screw plug of the opening device is twisted/turned, the septum over the pre-cut hole is cut or torn. If the cutting or cutting resistance in the laminated film is too high, the attached opening means of the package will become difficult to open, for example when very strong polymer films or layers are used as material layers in the film. Also, if the adhesion between the layers of the laminated film is low, delamination and tear edges of the material can occur, making it unsightly to open. When using the dense surface barrier paper of the present invention as the main inner barrier layer, the laminated film is mechanically stable and has a high lamination quality, ie without any cracking or delamination between the layers before or after opening. Furthermore, also very thin dense surface papers, are particularly easy to cut or cut and seem to have perfect properties for such tear or cut or cut openability. The paper provides stability to the film during lamination, resulting in a good laminated film, and also provides stability to the film when it is cut through the opening device. Thus, the cut will be clean and provide a clean cut edge and is easy to do without much resistance when opening the screw plug.

The laminated packaging material obtained by the method of the invention may thus be a three-modular sandwich material comprising a cellulose-based spacer layer and a mechanically stable facing layer of oriented film or a high-density paper layer on the outside of the spacer, so Said laminate further comprises on the inside a dense surface barrier paper with at least some oxygen barrier properties which also acts as a facing layer on the other side of the spacer layer, and a heat-sealable layer and a tie or adhesive layer.

Alternatively, the laminated packaging material may be a dual modular sandwich material comprising a thinner or weaker than conventional corresponding liquid paperboard with or without an additional barrier coating applied thereto on top of its inner side. A dense surface barrier paper which also comprises the usual heat-sealable layer and a tie or adhesive layer.

According to an embodiment, the spacer layer may be a layer that creates a distance or spacing between significantly thinner layers of material with a higher Young's modulus and density, such as arranged on each side of the spacer layer The high-density paper layer, that is, the layer that provides stiffness and stability, is the so-called face layer. Additional layers can be arranged on the sides of the spacer layer, contributing to the overall sandwich structure, but the main effect can be seen with the paper face layer. The spacer layer may have low or no inherent bending stiffness and thus does not directly affect the bending stiffness of the laminated packaging material. Indirectly, however, it may contribute significantly to some layers having higher bending stiffness but lower thickness compared to the spacer layer through interaction with adjacent or laminated layers on both sides. In sandwich constructions, it is important to have at least one such facing or stiffness-enhancing layer on each side of the spacer layer. A paper face layer on each side of the spacer layer is required when the spacer layer has a low density and does not itself contribute much to the bending stiffness properties. When the distance between the paper face layers increases, the mechanical strength and bending stiffness of the laminated sandwich structure will also increase.

A suitable cellulose-based material for the spacer layer may be, for example, so-called foamed cellulose, ie foam-formed fibrous cellulose, which is a fibrous material with adjustable density that can be produced by a foam-forming process.

The bulk layer comprising expanded cellulose thus has a density below 700 kg/m ³ , such as 100 to 600 kg/m ³ , such as 100 to 500 kg/m ³ , such as 200 to 500 kg/m ³ , such as 200 to 400 kg/m ³ , eg a density of 300 to 500 kg/m ³ , eg 300 to 400 kg/m ³ . The lower the density of the expanded cellulose layer, the more cost-efficient the raw material consumed, while above 300 kg/m ³ a better resistance to thinning of the expanded cellulose is obtained. According to one embodiment, the optimum density of expanded cellulose for laminated packaging has been extrapolated to be 300-500 kg/m ³ , in particular 300-400 kg/m ³ .

Thus, the method of the invention enables the introduction of expanded cellulosic host material into laminated packaging materials suitable for the production of packaging containers for food products, in particular for liquid and semi-liquid food products. Such lamination of the bulk layer to the polymer layer can be performed by melt extrusion operations such as extrusion coating and extrusion lamination of polymer layers. Extrusion is usually carried out at elevated temperatures, for example up to about 330°C in the case of molten low density polyethylene. Contrary to the case of bulk layers of other foamed polymer layers, such temperatures have been shown not to be a major problem for bulk layers comprising expanded cellulose. Compared with usual foamed polymer layers and especially foamed polyolefin layers, foamed cellulose has low heat transfer and thermal stability above 300°C, which will provide the most realistic and Viable alternative to foamed polymers. It has been seen that at relatively low densities of 300-400 kg/ ^m3 , expanded cellulose does not significantly lose thickness in extrusion lamination operations and maintains sufficient layer strength, or so-called z-strength, for use in Packaging laminates are used for the purposes of the present invention.

The bulk layer comprising expanded cellulose as described in the aspects and embodiments herein further provides the desired strength against delamination, ie it does not delaminate easily under standard conditions. Delamination strength can be determined for example by the Huygen Internal Bonding Energy test rig which follows TAPPI T 569 and provides J/ ^m2 values where packaging materials here are between 60-300J/m2, eg ^60-250J /m ² , such as 80-200J/m ² , such as 140-200J/m ² . In some aspects and embodiments, the bulk layer provides distance between the barrier layer and the outer printed substrate layer and thereby enables custom laminate packaging construction. Thus, the bulk layer comprising expanded cellulose provides delamination strength in combination with compressive strength in the thickness (ZD) direction and provides sufficient distance between the barrier layer and the decorative layer.

Foamed cellulose can be produced by mixing cellulose fibers with a foaming fluid, such as water, or optionally a surfactant, such as sodium dodecyl sulfate (SDS). The amount of surfactant should be 0.1% to 20% by weight, such as 0.5% to 10% by weight, such as 1% to 5% by weight, such as 1.5% to 3% by weight. A rotor mixer on a common foam generator produces foamed cellulose. Foam is usually formed by introducing a gas into the mixture. Air is an example of a suitable gas. Another suitable gas is oxygen. Typically, the gas enters the mixture through a vortex caused by pressurized gas and agitation. Typically, cellulose is provided as a liquid dispersion comprising cellulose fibers. An example of a liquid is water. Some examples of cellulose fibers are cellulose-based fibers such as chemical pulp fibers, chemithermomechanical pulp fibers, thermomechanical pulp fibers, and kraft pulp fibers. For example, the fiber dispersion can be added to the foaming fluid after the foam has been generated from the fluid (including the surfactant). Optionally, a liquid dispersion comprising cellulosic fibers can be combined with a foaming fluid prior to foaming. Additives to control foam consistency may be added if necessary. Foamed cellulose produced as described herein is run through a nozzle arrangement ("headbox") in which pressure and forming tools produce a web of expanded cellulose which, after at least partial drying, is wound onto a reel and stored for future use in the preparation of packaging materials, for example. Optionally, the foamed cellulose web can be used in-line, ie, by directly applying additional layers to convert the foamed cellulose web into a laminated packaging material for liquid or semi-liquid food packaging. In order to obtain the desired dryness and density compared to conventional papermaking, additional or improved drying may be used as appropriate.

In some embodiments, foamed cellulose can be combined with other materials such as additives and/or microfibrillar cellulose and/or refined pulp and/or strength chemicals or agents such as starch and its derivatives, mannogalactan ( mannogalactans), carboxymethyl cellulose, melamine-formaldehyde colloid, urea-formaldehyde resin, polyamide-polyamine-epichlorohydrin resin mixture.

Another example of a spacer layer is made of so-called linerboard material, which generally has a fairly high density but a low inherent bending stiffness and other differences in mechanical properties that are still insufficient compared to conventional liquid packaging board, thus The dimensional and mechanical stability and thus the integrity and barrier properties of packages made of laminates having a bulk layer of this material deteriorate when manufactured by conventional production of packaging laminates.

In particular, the linerboard plies themselves have a significantly lower bending stiffness than laminated packaging materials suitable for liquid packaging. However, it still contributes to the overall bending stiffness of the laminated packaging material by providing spacing layers in a sandwich structure between facing layers with higher Young's Paperboard for liquid packaging has high compressive strength properties.

Cardboard is also called corrugated case material (CCM). The material required for corrugated carton material is corrugated core paper (or corrugated core paper). In use, the corrugated core paper has grooves (grooves) , and then arranged by gluing between two pieces of flat linerboard or liner mediums. This corrugated structure provides a high sandwich structure bending stiffness due to the corrugated middle layer, which acts as a spacer or spacer layer between two relatively thin liner layers. The two papers that make up containerboard are thus linerboard material, also commonly known as Kraft liner or test liner, and corrugated (or corrugated medium) material.

The two types of paper that make up containerboard are linerboard material and corrugated (or corrugated medium) material. Since containerboard is mainly made of natural unbleached cellulose fibers, it is usually brown or beige, but its hue can vary depending on the type of cellulose. However, white top linerboard also exists, which has a white top layer on one surface and is generally a more expensive material.

Hanging panels generally have a density below 850 kg/m ³ , for example below 835 kg/m ³ , are brown or beige in color and mainly comprise softwood fibers such as spruce and pine fibres. Accordingly, corrugated paper is usually used as a paper product for the corrugating medium in corrugated boxboard, with a density of 600-750 kg/m ³ , for example 600-700 kg/m ³ , usually about 650 kg/m ³ . Corrugated is brown or beige and contains mainly short fibers, just like linerboard, and is usually a low-cost, low-quality paper that is not suitable by itself for liquid carton packaging. However, when used as a spacer layer in a sandwich construction, it can work well for its purpose and at a fairly low price if it is of the approved kind and combined in the correct manner with the appropriate layers in such packaging laminates .

However, corrugated medium will form the spacer layer by being a less rigid, less costly fibrous material that is non-corrugated and can provide adequate Pitch. Corrugated spacers, ie well structured spacers, are outside the scope of this invention. The technical meaning and requirements of corrugated carton materials for liquid carton laminated packaging materials will be very different, and will not be discussed here.

The fibers usually used to make containerboard materials can be roughly divided into two categories: recycled fibers and new fibers, namely virgin fibers. The properties of paper depend on the structural properties of the various fibers that make up the paper. In general, the higher the virgin fiber content, the stronger and stiffer the corrugated or linerboard material (higher compressive strength). The corrugated material explored for the purpose of the present invention is a semi-chemical corrugated paper made of 100% virgin fibers made from hardwoods such as birch from Power flute. Birch is one of the best corrugated raw materials. Its structure contains high concentrations of lignin and hemicellulose. The pulping process preserves the naturally highly hydrophobic lignin and modifies the remaining hemicellulose, thus protecting the fiber's soft and flexible cellulose core. This provides higher stiffness and creep properties. When used in liquid packaging, to cope with the liquid and high humidity conditions of this new use and application, commercially available corrugated paper materials require supplementation with one or more additional sizing agents during pulping or cellulosic web manufacture. Conventional sizing techniques and chemicals (AKD, ASA, rosin, etc.) can be used on corrugated materials to meet the necessary requirements for specific products.

Linerboard made from virgin fibers is known as kraftboard, while linerboard from recycled fibers is known as testliner. It is also possible to mix virgin fibers and regenerated fibers. The kraft linerboard should have at least 80% by weight virgin fibers, preferably 100% by weight. The fibers used for recovered linerboard are longer than those used in corrugated board, and since linerboard is originally used for the outer side paper layers of carton material, they are also sized with sizing agents to withstand varying degrees of humidity and wet conditions .

Therefore, the linerboard material has a lower bending stiffness than the corresponding cardboard used for liquid packaging, but on the other hand, has a higher SCT index than normal liquid cardboard material or other paper or cellulose materials suitable in this case , that is, a higher SCT value per gram unit in the machine direction (MD). Bending stiffness is not normally measured on linerboard materials as they are used in corrugated carton manufacturing anyway, but has been measured on the corresponding grammage when excluding the printable coating (clay-coating) grammage Having a bending stiffness that is at least 30% lower, such as at least 40% lower, such as at least 50% lower than that of a liquid cartonboard of eg a triple- or double-sided type. In general, corrugated materials have a higher bending stiffness per gram than linerboard materials.

The SCT value is a property measured by the international standard ISO 9895 and is relied upon to compare different containerboard materials. The SCT or Short Compression Test measures the internal compressive strength of paper fibers in CD and MD, ie the in-plane compressive strength of the paper. This property varies according to the grammage of the particular paper being measured. The grammage of paper products is measured according to ISO 536.

Packages made from materials with a higher SCT index are better stackable and are therefore a measure of compressive strength per gram in the plane (x-y plane) of the carton material. Linerboard materials typically have a SCT index of over 30 Nm/g in MD and thus will provide i.a. the required compressive strength and stackability of liquid paperboard laminates. These materials do not need to be optimized for bending stiffness properties as they will only be used as (slotless) spacer layers in laminates for liquid carton packaging. Thus, while such linerboard materials were originally intended for use as facings in corrugated carton sandwich construction, for the purposes of the present invention they will be used as spacer plies in laminated constructions with laminated Additional facings to provide the bending stiffness required for liquid carton laminates.

For comparison, today's liquid paperboard materials have an SCT index of about 25 Nm/g, but are then optimized for all other properties as well, since they are relied upon as the main provider of dimensional stability in liquid carton laminate packaging. When replacing today's optimized liquid paperboard with a low-cost spacer layer in a sandwich structure in a laminate, this spacer layer needs to have a higher SCT index above 30 Nm/g in order to compensate when removing the prior art paperboard properties that are lost.

Since the new spacer layer will be laminated to the other facing layers in the sandwich structure in the laminate, there is no need to provide a white or smooth (eg clay coated) printing surface on the spacer layer itself. In this respect too, containerboard material is therefore a suitable material for such a spacer layer.

Regarding moisture resistance, these materials may have a Cobb water adsorption value below 35 ^g /m2 in order to perform better in liquid carton packaging laminates. Cobb values are measured according to ISO 535 and are already achieved by most linerboard materials, while some corrugated materials may require additional sizing for use as a grooveless spacer in liquid carton packaging laminates. Accordingly, the linerboard material in the bulk layer comprises at least one sizing additive.

In another embodiment, the spacer layer may comprise a combination of different cellulose or paper types. If the spacer layer comprises expanded cellulose, the expanded cellulose portion is at least 20%, such as at least 25%, such as at least 30%, such as at least 40%, of the thickness of the chassis layer. Percentages can be determined by examining a cross-section of the packaging material in a microscope.

When going down from conventional liquid paperboard to this insufficient or lower density cellulose material for the body layer, it has been seen that the aluminum foil barrier layer laminated to the inside of the body layer develops fine cracks and is no longer permeable to gas Dense. This is a result of the fact that the aluminum foil is not supported by the weaker bulk layer, allowing the aluminum foil to have a higher degree of freedom of movement, thus creating more strain and stress on it. While saving costs in terms of paperboard material, it was therefore considered necessary to spend more resources on barrier material to compensate for the loss of barrier properties. Another idea is of course to somehow replace the aluminum foil with a different, better barrier layer, but this has until now been considered expensive to wish and/or expensive to laminate with each other in order to provide the desired barrier properties and Several different barrier layers were placed.

In another embodiment, the body layer mainly comprises a layer of spacer material, but may additionally comprise one or two integrated paper layers, the paper layer having a relatively high Young's modulus but a lower thickness compared to the spacer layer, In order to provide a certain mechanical strength and bending stiffness for the final laminated material produced.

The final laminate may comprise at least one such relatively thinner and stiffer paper disposed on each side of the spacer layer. With this structure, the thinner and stiffer papers act like the flanges of an I-beam structure or the facing of a sandwich structure, making the sandwich mechanically (e.g., with respect to bending stiffness and compressive strength in all directions within the material) aspect) is stable.

Suitable such stabilizing paper facings can be found in thin kraft paper, greaseproof paper or parchment paper. They should have a grammage of 20-100 g/m ² , for example a grammage of 30-70 g/m ^{2 , for example a grammage of 30-60 g/m 2 and} a density of 600-1500 kg/m ³ .

Typically, the paper face layer should have a Young's modulus of 1 to 10 GPa, such as 5 to 10 GPa.

The paper face layer can be included in the laminate structure in different ways. For example, when the spacer layer itself has a higher density and inherent stiffness, such as a linerboard material spacer layer, the body material layer may comprise a layer of corrugated material, and this thinner, stiffer layer on only one side of the spacer layer. Or higher density paper surface layer. For the final laminate it may be sufficient to have only a dense surface barrier paper on the inside and a facing layer of a less stable different material (eg oriented plastic film) on the outside of the spacer layer. Alternatively, a paper face layer may also be included in the outer material module to be laminated to the corrugated material layer.

The bending stiffness of packaging material laminates can be derived from the thickness and Young's modulus of the individual layers. In order to balance the mechanical properties of the sandwich laminate structure, the facing layers of the interlayer should be arranged on respective sides of the spacer layer such that they have substantially equal tensile stiffness. Tensile stiffness is given by the product of Young's modulus and thickness. This can be adjusted by varying the thickness and Young's modulus of the paper, and in cases where there is more than one such paper facing layer on one side of the spacer layer, there are limitations for calculating the total bending stiffness of a particular combination of facing layers. formula.

By tailoring the sandwich structure so that the thicker paper face layer on the outside can be separated from the spacer layer and at the same time make up the print base layer, it allows for printing background color, texture and pattern differences, as thin as possible, despite the features used for lamination in Higher Young's modulus barrier coating base paper in the inner material module Barrier coating process efficiency can also be increased by using thinner substrates and thus fewer base rolls in e.g. vacuum coating processes. Asymmetries in the properties of the paper face layer can be balanced by other layers in the structure so that symmetry with respect to the centerline of the spacer layer is still obtained and curling can be avoided.

In embodiments where the bulk layer comprises expanded cellulose, the final laminate may include a paper face layer disposed on each side of the spacer layer in order to provide sufficient stability to the final laminated packaging material.

Thus, the body material may comprise a spacer layer and a dense surface barrier paper as a face layer on the first side (inner side) of the spacer layer, while the outer material module further comprises a paper face layer to be laminated to the body and the second side of the spacer layer. on the side (outside).

Alternatively, the body material layer may comprise a spacer layer and an integrated paper face layer on the second side of the spacer layer, while the inner material module comprises a barrier paper face layer, thus laminated to the body and the first side of the spacer layer. Alternatively, the inner material module may comprise a barrier coated oriented polymer film as a face layer to interact with the integrated paper on the other side of the spacer layer.

Alternatively, the body material may comprise a spacer layer and an integrated paper face layer on each side of the spacer layer.

The spacer layer may in one embodiment be a fibrous layer made by a foam forming process and have a grammage of 150 ^g /m2 and a thickness of 600 μm, and it may have 60-80 g/m ² (eg 70 g/m ² ) high-density paper.

By removing the decorative function of today's traditional liquid paperboard body layer (i.e., a white printable surface, colored decorative patterns can be printed on the white printable surface) and removing at least some of its bending stiffness from the body layer, and instead laminating low quality A separate printed substrate layer on the outside of the main body layer to the main body layer can provide greater flexibility in the manufacturing process of packaging laminates of different appearances at a lower cost and shorter lead time from order to delivery. Therefore, it is easier to change the appearance of the packaging container without affecting the manufacturing process or raw materials, other than just replacing the printed substrate and the actual printed decorative pattern. The printing substrate can be white, brown, colored, metallized, etc. At the same time, due to the sandwich effect of the layers of the laminate as a whole, it is still possible to obtain a mechanically and dimensionally stable packaging container with a good appearance.

Suitable printing substrates may be stably stretched and pre-fabricated polymer films selected from polyester-based such as oriented or non-oriented polyethylene terephthalate ester (PET), oriented or non-oriented 2,5-furandicarboxylate (PEF), oriented or non-oriented polybutylene terephthalate (PBT), polyethylene naphthalate ( PEN), polyamides, e.g. non-oriented or oriented polyamides (PA, OPA, BOPA), ethylene vinyl alcohol copolymers (EVOH), polyolefins such as polypropylene, mono- or biaxially oriented polypropylene (PP, OPP, BOPP), polyethylene such as oriented or non-oriented high density polyethylene (HDPE), linear low density polyethylene (LLDPE) and cyclic olefin copolymer (COC), and any of the blends of any of said polymers or a group of multilayer films having a surface layer comprising any of said polymers or blends thereof.

The printing substrate may have a printable surface which is a clay coated white paper surface or a brown natural paper surface or a metallized film or metallized paper surface.

The outer material modules may be laminated by applying an aqueous adhesive composition in an amount of 0.5 to 4 g/m ² , for example 1 to 3 g/m ² , to one of the surfaces to adhere to each other and then pressing them together to the main material.

The inner material modules can be laminated to the body material by applying an amount of 1-4 ^g /m2 of the aqueous adhesive composition to one of the surfaces to adhere to each other and then pressing them together.

In laminating the inner and outer material module webs to the body layer web, different methods and lamination materials can be used. Melt extrusion lamination with intermediate molten thermoplastic binding polymers has been mentioned above and is a common way of laminating two webs to each other.

When the surfaces to be laminated to each other are all paper or cellulose based surfaces, good adhesion between the laminated surfaces will result. Certain types of surfaces may require an oxidative pretreatment of the surface prior to adhesion to another surface, or alternatively, or in addition, the bonded polymer to be melt-extruded may at least partially comprise a viscous thermoplastic polymer, i.e. Polymers with functional groups that have an affinity for various surfaces, usually carboxylic acid or maleic anhydride groups.

Suitable for use as a tie layer on the inside of a laminate (i.e. between an outside heat-sealable layer and a barrier or primer-coated substrate layer) or for bonding a barrier film to a body in single or multiple such tie laminate layers The adhesive polymer of the layer can also be a so-called adhesive thermoplastic polymer, such as a modified polyolefin, which is mainly based on LDPE or LLDPE copolymers or has monomer units (such as (meth)acrylic acid monomers or maleic anhydride (MAH) monomer) functional groups (such as carboxylic acid or glycidyl functional groups), (ie, ethylene acrylic acid copolymer (EAA) or ethylene methacrylic acid copolymer (EMAA)), ethylene-(methyl ) glycidyl acrylate copolymer (EG(M)A) or MAH grafted polyethylene (MAH-g-PE). Another example of such modified or tacky polymers are so-called ionomers or ionomer polymers. Preferably, the modified polyolefin is ethylene acrylic acid copolymer (EAA) or ethylene methacrylic acid copolymer (EMAA).

A corresponding modified polypropylene based thermoplastic adhesive or tie layer may also be useful, depending on the requirements of the finished packaging container.

Such adhesive polymer layers or tie layers are usually applied together with corresponding outer layers or additional bulk-to-barrier bonding layers of bulk layers and barrier layers in a coextrusion coating operation.

The adhesive may be applied as an aqueous adhesive solution or composition, and it may be applied to one surface to be laminated to each other and then bonded to the other surface in a lamination station comprising one or Multiple lamination pressure nips.

Preferably, and generally, there should only be one lamination nip in the lamination station in order to apply as little pressure as possible to the weaker, low density spacer layer. However, in some embodiments it is possible, in order to enhance adhesion, by applying a lower nip pressure, but through several successive nips or through an extended nip arrangement, several successive rolls A gap would be beneficial.

The laminate packaging material of the present invention has a higher content of fibers and materials from renewable resources, which is advantageous from an environmental point of view. Furthermore, by increasing the proportion of cellulose fibers in the material, it becomes easier to handle in the recycling process, especially if at the same time the proportion of the amount of thermoplastic polymer layer and aluminum foil can be reduced. This is an advantageous effect, for example, if the lamination of the cellulose-based modules can be accomplished by absorption lamination with aqueous adhesives, i.e. a lamination method in which only very small amounts of The polymeric adhesive and bonds the two surfaces to be laminated together, while the aqueous medium or solvent is absorbed into the cellulose network of the laminated layer without further drying or heating. Thus, although less thermoplastic binding material is required, for example in melt extrusion lamination, the relative proportion of paper or cellulose-based material layers in the packaging material increases, and furthermore, due to the various components included in the laminated packaging material An effective combination of the properties of the material layers, so the barrier layer can be down-gauged.

Examples of suitable thermoplastic polymers for the outermost and innermost heat-sealable liquid-tight layers in the laminated packaging material of the present invention are polyolefins such as polyethylene and polypropylene homopolymers or copolymers, preferably polyethylene , more preferably a polyethylene selected from low density polyethylene (LDPE), linear LDPE (LLDPE), single-site catalyst metallocene polyethylene (m-LLDPE) and blends or copolymers thereof. According to a preferred embodiment, the outermost heat-sealable and liquid-tight layer is LDPE, while the innermost heat-sealable liquid-tight layer is m-LLDPE and LDPE for optimum lamination and heat-sealing properties Blend composition. The outermost and innermost thermoplastic polymer layers can be applied by (co)extrusion coating of molten polymer to the desired thickness. According to another embodiment, the outermost and/or innermost liquid-tight and heat-sealable layers may be applied in the form of prefabricated, oriented or non-oriented films. Alternatively, when only a low thickness of this outermost layer is required, or when such a process can be preferred for other reasons, the outermost heat-sealable layer can be applied by coating from an aqueous dispersion of thermoplastic polymer. Liquid-tight and protective thermoplastic polymer layer.

The same thermoplastic polyolefin-based materials listed above for the outermost and innermost layers, especially polyethylene, are also suitable for the tie layer on the inner side of the laminate, i.e. in the bulk or core layer (e.g. paper or cardboard) Bonding ply with pre-laminate material including barrier film or another film layer.

In cases where the dense surface barrier paper provides only a low level of gas barrier properties, there may be other barrier layers, including those with barrier coatings (such as dispersion-coated or liquid film-coated barrier coatings, or vapor-deposited barrier coatings). coating) film substrate.

Suitable film substrates for such barrier films are polymer films selected from polyester-based such as oriented or non-oriented polyethylene terephthalate (PET), oriented or non-oriented 2 , 5-Ethylene furandicarboxylate (PEF), oriented or non-oriented polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyamides, e.g. non-oriented Or oriented polyamide (PA, OPA, BOPA), ethylene vinyl alcohol copolymer (EVOH), polyolefin, such as polypropylene, mono- or biaxially oriented polypropylene (PP, OPP, BOPP), polyethylene, such as oriented or non- Films of any of oriented high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE) and cyclic olefin copolymer (COC), and blends of any of said polymers, or having a film comprising any of said A group consisting of multilayer films with surface layers of polymers or blends thereof.

According to some embodiments, the barrier properties may be provided by a polymer layer or layers or one or more barrier polymer films, while in other embodiments the polymer of the film is used only for the purpose of providing a base for a subsequently applied barrier coating .

Additional oxygen barrier properties can thus be provided by thin liquid film coatings (e.g. barrier polymers) applied as dispersions or solutions in liquid media or solvents onto a substrate such as paper or a polymeric film substrate and subsequently dried to a thin barrier coating. It is important that the dispersion or solution is uniform and stable to form a uniform coating with uniform barrier properties. Examples of suitable polymers for aqueous compositions are polyvinyl alcohol (PVOH), water dispersible ethylene vinyl alcohol (EVOH) or polysaccharide based water dispersible or soluble polymers. Such dispersion coatings or so-called liquid film coating (LFC) layers can be made very thin, down to a tenth of a gram, if the dispersion or solution is homogeneous and stable, i.e. well prepared and mixed per square meter, and can provide a high-quality homogeneous layer. PVOH has excellent oxygen barrier properties in dry conditions and also provides very good odor barrier properties, that is, the ability to prevent odorous substances from entering the packaging container from the surrounding environment (for example, in a refrigerator or storage room). Becomes important when storing packages for long periods of time. Furthermore, such liquid film-coated polymer layers from water-dispersible or hydrolyzable polymers generally provide good internal adhesion to adjacent layers, which contributes to good integrity of the final packaging container.

Suitably, the polymer may be selected from vinyl alcohol based polymers (such as PVOH or water-dispersible EVOH), polysaccharides (such as starch or starch derivatives), cellulose nanofibrils (CNF), nanocrystalline cellulose (NCC), Hemicellulose or chitosan or other cellulose derivatives, water dispersible polyvinylidene chloride (PVDC) or water dispersible polyester or a combination of two or more thereof.

More preferably, the polymeric binder is selected from PVOH, water dispersible EVOH, polysaccharides such as starch or starch derivatives, chitosan or other cellulose derivatives, or a combination of two or more thereof.

Such barrier polymers are therefore suitable for application by means of liquid film coating processes, ie in the form of aqueous or solvent-based dispersions or solutions, which are dispersed on the substrate as a thin, homogeneous layer on application and then dried.

Aqueous compositions generally have certain environmental advantages. Preferably, the liquid gas barrier composition is water based since such compositions are generally more work environment friendly than solvent based systems.

As mentioned briefly above, polymers or compounds with functional carboxylic acid groups can be included to improve the water vapor and oxygen barrier properties of PVOH coatings. Suitably, the polymer having functional carboxylic acid groups is selected from ethylene acrylic acid copolymer (EAA) and ethylene methacrylic acid copolymer (EMAA) or mixtures thereof. A particularly preferred barrier layer mixture consists of PVOH, EAA and inorganic layer compounds. The EAA copolymer is then included in the barrier layer in an amount of about 1-20% by weight based on dry coating weight.

Further examples of polymeric binders suitable for liquid film coating that provide oxygen barrier properties are polysaccharides, especially starch or starch derivatives, such as preferably oxidized starch, cationic starch and hydroxypropylated starch. Examples of such modified starches are hypochlorite oxidized potato starch (Raisamyl 306 from Raisio), hydroxypropylated corn starch (Cerestar 05773) and the like. However, other starch forms and polysaccharide derivatives can also provide gas barrier properties to some extent.

Most preferably, however, the gas barrier polymer is PVOH because it has all the good properties mentioned above, namely film forming properties, gas barrier properties, cost efficiency, food compatibility and odor barrier properties.

Gas barrier compositions based on PVOH perform best when the PVOH has a degree of saponification of at least 98%, preferably at least 99%, but PVOH with a lower degree of saponification will also provide oxygen barrier properties.

According to another embodiment, the liquid composition may additionally contain inorganic particles to further improve the oxygen barrier properties.

The polymeric binder material can be mixed, for example, with layered or flake-shaped inorganic compounds. With the layered arrangement of the flake-like inorganic particles, oxygen molecules have to migrate a longer path through the oxygen barrier layer via a tortuous path than the normal straight path through the barrier layer.

Inorganic layered compounds are so-called nanoparticulate compounds dispersed in an exfoliated state, that is, flakes of layered inorganic compounds are separated from each other by a liquid medium. The layered compounds are therefore preferably swellable or cleavable by polymer dispersions or solutions which have penetrated the layered structure of the inorganic material with the dispersion. It may also be swollen with a solvent before adding to the polymer solution or polymer dispersion. Thus, the inorganic layered compound is dispersed in a layered state in the liquid gas barrier composition and in the dried barrier layer. There are many chemically suitable nanoclay minerals, but the preferred nanoparticles are those of montmorillonite, such as pure montmorillonite or sodium-exchanged montmorillonite (Na-MMT). The nano-sized inorganic layered compound or clay mineral preferably has an aspect ratio of 50-5000 and a particle size of at most about 5 μm in the exfoliated state.

Suitable inorganic particles consist essentially of layered bentonite particles having an aspect ratio of 50 to 5000.

Preferably, the barrier layer comprises from about 1 to about 40 weight percent, more preferably from about 1 to about 30 weight percent, most preferably from about 5 to about 20 weight percent inorganic layered compound, based on dry coating weight. If the amount used is too low, the gas barrier properties of the coated and dried barrier layer will not be significantly improved compared to when the inorganic layered compound is not used. If the amount is too high, the liquid composition becomes more difficult to apply as a coating and more difficult to handle in the reservoir tank and conduit of the applicator system. Preferably, the barrier layer comprises from about 99 to about 60 weight percent, more preferably from about 99 to about 70 weight percent, most preferably from about 95 to about 80 weight percent polymer, based on dry coating weight. Additives such as dispersion stabilizers and the like may be included in the gas barrier composition, preferably in an amount not exceeding about 1% by weight based on the dry coating. The total dry content of the composition is preferably from 5 to 15% by weight, more preferably from 7 to 12% by weight.

According to various preferred embodiments, the inorganic particles mainly consist of layered talc particles with an aspect ratio of 10-500. Preferably, the composition comprises talc particles in an amount of 10-50% by weight, more preferably 20-40% by weight, based on dry weight. Below 20 wt%, the gas barrier properties do not increase significantly, while above 50 wt%, the coating may be more brittle and brittle due to lower internal cohesion between particles in the layer. The amount of polymeric binder appears to be too low to surround and disperse the particles and laminate them to each other in layers. The total dry content of this liquid barrier composition from PVOH and talc particles may be between 5 and 25% by weight.

Surprisingly good oxygen barrier properties can be obtained when using colloidal silica particles exhibiting a particle size of 3-150 nm, preferably 4-100 nm and even more preferably 5-70 nm, said The particles are preferably amorphous and spherical. Furthermore, the use of colloidal silicon dioxide particles has the advantage that the liquid barrier composition can be applied at a dry content of 15-40 wt. demand is reduced.

Less preferred alternatives to inorganic particles according to the invention are particles of kaolin, mica, calcium carbonate and the like.

When using inorganic particles to provide oxygen barrier properties, the preferred polymeric binder is PVOH, due in part to its favorable properties mentioned above. In addition, PVOH is advantageous from a mixing point of view, that is, it is generally easy to disperse or exfoliate inorganic particles in aqueous PVOH solutions to form a stable mixture of PVOH and particles, thus enabling good coating films with uniform composition and morphology.

The oxygen barrier layer may be applied in a total amount by dry weight of 0.1 to 5 g/m ² , preferably 0.5 to 3.5 g/m ² , more preferably 0.5 to 2 g/m ² . Below 0.5g/ ^m2 , there may not be any effect of further filling and closing the pores on the surface of the substrate, and gas barrier properties cannot be achieved at all, while above 5g/ ^m2 , the coating layer will not give the packaging Laminates bring cost benefits due to the high cost of barrier polymers in general and the high energy costs due to evaporation of liquids. PVOH achieves recognizable oxygen barrier levels at 0.5 g/ ^m2 and above, and achieves a good balance between barrier performance and cost between 0.5 and 3.5 ^g /m2.

As two partial layers, the oxygen barrier layer can be applied in two consecutive steps with intermediate drying. When applied as two partial layers, each layer is suitably applied in an amount of 0.1 to 2.5 g/m ² , preferably 0.5 to 1 g/m ² , and allows a lower amount of liquid gas barrier composition to form a higher quality overall layer . The two partial layers can each be applied in an amount of 0.5-2 g/m ² , preferably 0.5-1 g/m ² .

Additional barrier coatings may also be applied by means of physical vapor deposition (PVD) or chemical vapor deposition (CVD) onto substrate surfaces, such as dense surface barrier paper substrates or film materials. The substrate material itself may also have some properties, but above all it should have suitable surface properties to be suitable for receiving vapor deposited coatings and should work effectively in the vapor deposition process.

Thin vapor-deposited layers are generally only nanometers thick, that is, have a thickness on the order of nanometers, for example from 1 to 500 nm (50 to ), preferably from 1 to 200 nm, more preferably from 1 to 100 nm, most preferably from 1 to 50 nm.

A common type of vapor-deposited coating, usually with some barrier properties, especially water vapor barrier properties, is a so-called metallization layer, such as an aluminum metal physical vapor deposition (PVD) coating.

This vapor-deposited layer consisting essentially of aluminum metal may have a thickness of 5 to 50 nm, which corresponds to less than 1% of the aluminum metal material present in aluminum foils of conventional thickness used for packaging, eg ie 6.3 microns. Although vapor-deposited metal coatings require significantly less metallic material, they provide at best low levels of oxygen barrier properties and need to be combined with additional gas barrier materials to provide a final laminate with adequate barrier properties. On the other hand, it can be supplemented with a further gas barrier layer, which does not have water vapor barrier properties but is quite sensitive to moisture.

Other examples of vapor deposited coatings are aluminum oxide (AlOx) and silicon oxide (SiOx) coatings. Typically, such PVD coatings are more brittle and less suitable for incorporation into packaging materials by lamination. As an exception metallization layers, although produced by PVD, have suitable mechanical properties for the laminate, but generally offer a lower barrier to oxygen.

Other coatings that have been investigated for laminated packaging materials can be applied by means of plasma-enhanced chemical vapor deposition (PECVD), in which gas-phase compounds are deposited onto the substrate in a more or less oxidizing environment. Silicon oxide coatings (SiOx) can also be applied eg by PECVD processes and very good barrier properties can then be obtained under certain coating conditions and gas formulations. Unfortunately, SiOx coatings exhibit poor adhesion when laminated to polyolefin and other adjacent polymer layers by melt extrusion lamination and the laminate is exposed to wet or highly humid packaging conditions performance. Particularly expensive adhesives or tacky polymers are required to achieve and maintain sufficient adhesion of the type of packaging laminate used for liquid carton packs.

The vapor-deposited coating may be a barrier layer of amorphous hydrogenated carbon (so-called diamond-like carbon (DLC)) applied by a plasma-enhanced chemical vapor deposition process (PECVD). DLC defines a class of amorphous carbon materials that exhibit some of the typical properties of diamond. Preferably, a hydrocarbon gas (eg acetylene or methane) is used as process gas in the plasma used to produce the coating. As noted above, it has now been seen that such DLC coatings provide good and adequate adhesion to adjacent polymer or adhesive layers in laminated packaging under wet test conditions. Particularly good adhesion to adjacent laminated polymer layers (i.e. polymer layers attached to or coated on DLC barrier coatings) has been seen with polyolefins, especially polyethylene and polyethylene-based copolymers compatibility.

Therefore, the DLC barrier coating is a liquid-filled packaging container made of a packaging laminate comprising a barrier film with a barrier coating or a barrier paper. Good barrier properties for various substances that migrate through such laminates in an outward or outward direction, and provide good barrier properties and integrity by resulting in excellent adhesion of adjacent polymer layers in the laminate. Therefore, a barrier film with a DLC barrier coating from a base layer of polyester or polyamide can provide packaging laminates and packaging containers with oxygen barrier properties and water vapor barrier properties for long-term environmental storage, such as storage for up to 2-6 months, such as up to 12 months. In addition, DLC barrier coatings provide good barrier properties for various aroma and flavor substances present in the packaged food, for low-molecular substances that may appear in adjacent material layers, and for odors and gases other than oxygen . In addition, DLC barrier coatings have good mechanical properties when coated on polymeric film substrates, and when laminated into paperboard-based packaging laminates, resist lamination and subsequent fold forming of the packaging laminate as well as Seal it into a filled package.

DLC coatings also have the advantage of being easily recyclable without leaving residues in the recycled content containing elements or materials that do not occur naturally in nature and our surrounding environment.

The use of the aforementioned tacky polymers should not be necessary for adequate bonding to the particularly metallized layer or DLC barrier coating of the present invention. The metallized adhesion to the polyethylene layer is good, and also with regard to DLC, sufficient and sufficient adhesion to the polyolefin layer as an adjacent layer has been found to a level of at least 200 N/m, for example at least is 300N/m. Adhesion measurements were performed at room temperature 24 hours after LDPE lamination with a 180° peel force tester (Telemetric Instrument AB). The stripping was done at the DLC/LDPE interface, the stripping arm was the barrier film. A drop of distilled water was added to the peeled interface during the peeling process in order to also evaluate under wet conditions, i.e. the laminated packaging material has been passed through the layers of the material, from the liquid stored in the packaging container made of the laminated material. Adhesion when saturated by migrating moisture and/or when saturated by storage in humid or highly humid environments. The given adhesion values are given in N/m and are the average of 6 measurements.

A dry adhesion of greater than 200 N/m thus ensures that the layers do not delaminate under normal packaging manufacturing conditions (eg when bending and folding to form a laminate). This same level of wet bonding ensures that the layers of the packaging laminate do not delaminate during shipping, distribution and storage after filling and package formation. The inner bonding polymer layer can be coated directly onto the polymer film substrate on which the DLC barrier layer is coated by using common techniques and machinery such as those used for laminating aluminum foils, especially for thermal layers Coating (extrusion) of polymer layers from molten polymers to those of the DLC barrier layer. Furthermore, it is feasible to use a prefabricated polymer film and bond it directly to the barrier-coated carrier film by melting it locally, for example by applying heat with a heating cylinder or heated roll. From the above it can be seen that DLC barrier films can be processed in a process of lamination and conversion into laminated packaging materials (ie by extrusion lamination and extrusion coating) in a similar manner to aluminum foil barrier layers. The lamination equipment and method do not require any modification, such as by adding specific tacky polymers or adhesive/tie layers, which may be required in plasma coated materials. Additionally, the new barrier film, including a DLC barrier layer coated thereon, can be made as thin as aluminum foil without adversely affecting barrier properties in the final food packaging.

When making the laminated packaging material of the present invention, it has been seen that in asymmetrical laminates having a layered structure with unequal extensional stiffness properties on both sides of the spacer layer, a problem known as moisture induced curling may arise, That is, flat material does not remain flat when placed on a flat surface, but rolls up so that the edges lift above the plane of the flat portion of the packaging material and bend toward each other. Another advantage of flat laminated side panels in packaging containers is that gripping stiffness will be improved. This is due to the absence of the original "defect" of the candy bar, which is deflection. Of course, running flat packaging material through a filling machine is less of a problem than running curly and curved packaging material.

It has been seen that curling is primarily prevented by matching the face layers on each side of the spacer layer to have equal overall tensile stiffness. By doing so, it has surprisingly been seen that due to the flatness of the laminate sheet, the compressive strength of the laminate in the x-y direction will also increase. This means that folded packaging containers, for example made of laminated packaging material, can be stacked on top of each other during distribution and storage with higher loads than liquid food packages sold today.

Thereby, a package made of such laminated packaging material of symmetrical dimensions with a paper face layer on each side of the spacer layer in a sandwich structure can obtain improved package integrity, i.e. the package integrity is improved, and The laminate is less susceptible to damage only by handling and shipping and less prone to cracks in the spacer layer.

Laminates of all kinds, including barrier layers that protect packaged food from slow migration of oxygen and other gases and vapors, can better resist damage and The integrity of the filled and sealed package is thus also improved from this point of view.

Therefore, another aspect of improving package integrity is improving adhesion between layers. Particularly good initial adhesion is obtained between dispersion or solution applied barrier coatings having hydrophilic functionalities such as hydroxyl and carboxyl groups and adjacent layers such as polyolefins and polyethylene. Vapor-deposited metallized coatings and DLC PECVD coatings have been shown to provide very good adhesion properties to adjacent organic polymer layers and films such that in laminated packaging these layers are in good contact with their adjacent layers There is no need to use additional primers or adhesives in between.

Nevertheless, it has been shown that, at least with metallized barrier coatings, the further enhanced adhesion by lamination to an adjacent tie polymer or adhesive polymer layer also surprisingly reduces the oxygen barrier of the laminate. Sexuality is further enhanced and to a higher degree than anyone can imagine.

Additional oxygen barrier properties may be provided by further including a polymer layer as a barrier layer to migrating free fatty acids, such as polyamide in the first pre-laminate to be laminated to the body layer. Especially when polyamide is added on the inner side of the metal barrier layer, it can prevent the free fatty acid of the packaged food from migrating from the food to the metal barrier layer, so the barrier properties of the barrier layer remain intact and the inner polymer layer (heat seal) is separated from the metal barrier layer. The adhesiveness of the layers maintains a long shelf life.

The polyamide barrier layer may comprise 50% by weight or more polyamide and the remainder ethylene vinyl alcohol (EVOH) or polyethylene terephthalate (PET) or a similar polymer compatible with polyamide, and also Provides barrier properties against migration of free fatty acids and may be applied in an amount of 3-12 g/m ² , such as 3-10 g/m ² , such as 3-8 g/m ² , such as 3-6 g/m ² , depending on the amount to be The need for filling food and the balance with the cost of the materials used.

According to another embodiment, the polyamide barrier layer comprises an aromatic or semiaromatic polyamide polymer. This polyamide can provide better barrier properties against the migration of free fatty acids, which is why this combination is particularly advantageous for packaging fruit juices, for example. However, the most common polyamide suitable for cost-effective laminated packaging materials and the ease of fabrication of such coextrusion coated laminated structures is PA-6.

A particularly well-functioning paper face layer for the outside of a packaging laminate may be a greaseproof paper or a high-density paper that also has smoothed and pre-coated for subsequent barrier coatings, especially vapor deposition barrier coatings. coated surface. The paper face layer on the outside of the main body layer may in one embodiment be a coated or uncoated dense surface barrier paper of the same or a different type than the paper face layer laminated on the inside of the main body layer. Of course, this paper face layer will further contribute to the oxygen barrier of the final packaging laminate.

According to yet another embodiment, a packaging based as much as possible on biorenewable materials can be obtained. For example, packaging materials can be produced that have a cellulose-based spacer or body layer, a paper face layer with barrier properties, and also include a very thin nano-thin barrier coating. Moreover, thermoplastic polymers can be made from plants or organic materials, such as so-called green polyethylene.

Furthermore, the adhesives or tacky polymers used in the final laminated packaging in the lamination operation can be entirely bio-sourced and used only in very small quantities, which further adds to the renewable (and also cellulose fiber) Relative proportions of inclusions.

According to another aspect of the laminated packaging material obtained, the outermost heat-sealable layer of the laminated material may be provided as one or two preformed films. Thus, such a film may be pre-laminated to the barrier layer in a first pre-laminate to be laminated to the first side of the body layer, and/or pre-laminated to the second layer to be laminated to the body layer. Both sides are printed and decorated on the outer surface layer. When the film is pre-laminated to a barrier layer or printed decorative layer, especially if a pre-coat or integrated layer of adhesive polymer (such as EAA or EMAA) is present on one of the lamination surfaces, Layered onto other layers. Alternatively, it can be applied by melt extrusion lamination, which is more expensive due to the higher consumption of intermediate melt extrusion polymer, or by precoating with a small amount of aqueous adhesive without any drying step, the aqueous adhesive may penetrate into at least one paper or cellulose-based surface to be laminated.

In the general quest to reduce the cost of laminated packaging materials, the goal is to combine the properties of the various layers so that as few additional layers as possible are required.

Significant cost savings can be realized when the traditional liquid packaging paperboard of today's packaging laminates is replaced by a low cost, inappropriate bulk ply, so that additional resources can instead be spent on a variety of custom trim substrates for printing and Decorative laminated packaging material. Since the body layer as a spacer layer will no longer constitute the printing surface, i.e. the surface to be printed, the expensive clay coating can be omitted in the body layer and printed on the outside to be laminated to the body layer by other means A smooth white print surface is obtained on the backing paper. Such a printed substrate can be, for example, a colored or metallized film or a white printable paper cover. Alternatively, the white paper used to provide the white printed background surface can be pre-laminated to a transparent film (i.e. a reverse printed film) that is printed before its backside is laminated so that the printed decoration faces the white paper surface and is Transparent film base protection. Thus, in order to provide pre-lamination to the outside of the laminated packaging material, the printing and lamination of the outer white paper face layer and possibly other layers to the outermost heat-sealable layer can be performed in a pre-lamination operation. combine.

To further provide light barrier and whiteness, such films or papers may contain a white filler material, or in the case of paper, a clay coating, and may also, or alternatively, be a metallized layer. For some products and appearances of the packaging container, a metallized printed surface is preferred, and in other cases a colored printed surface or a brown natural cellulose printed surface. By separating the printed surface layer from the body layer, the versatility of possible appearance is possible and this is another advantage of the three-part modular laminated model of the present invention. It is even possible to include an additional oxygen barrier layer in the second pre-laminate in order to increase the overall barrier properties of the final laminate.

Examples and Description of Drawings

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, in which:

Figure 1a shows a schematic cross-sectional view of a specific example of a laminated packaging material with a dense surface barrier paper layer according to the invention,

Figure 1 b shows a schematic cross-sectional view of another such particular embodiment of a laminated packaging material having a dense surface barrier paper layer,

Figure 1c shows a schematic cross-sectional view of yet another particular embodiment of such a laminated packaging material with a dense surface barrier paper layer,

Figure 1d shows a schematic cross-sectional view of yet another particular embodiment of such a laminated packaging material with a dense surface barrier paper layer,

Figure 2a schematically shows an example of a method according to the invention for laminating a dense surface barrier paper layer to a host material,

Figure 2b schematically shows examples of different methods for laminating a dense surface barrier paper layer to a host material according to the invention,

Figures 3a, 3b, 3c and 3d show typical examples of packaging containers produced from a laminated packaging material according to the invention,

Figure 4 shows the principle of how to manufacture packaging containers from packaging laminates in a continuous web-feed, form, fill and seal process,

Figure 5 is a graph showing the oxygen barrier properties of a laminated packaging material from a cellulose corrugated body material layer compared to an existing paperboard-based laminated liquid packaging material of the same type laminated with an aluminum foil barrier layer in the same manner and formed filled A graph showing the degree of deterioration compared to when packaged in a bag,

Figure 6 is a diagram showing how OTR can be improved in conjunction with extrusion coating/lamination of metallized barrier layers with adhesive polymers,

Figure 7 is a graph showing how a dense surface barrier paper layer can provide light barrier properties,

Figure 8 shows how to increase the bending stiffness in a sandwich structure with a low stiffness spacer layer and a paper facing layer arranged or laminated on each side of the spacer layer.

Thus, a first embodiment of a laminated packaging material 10a according to the invention is shown in cross-section in FIG. 1a. It comprises a body material from a spacer layer 11a of cellulosic material, such as a foam formed fibrous cellulose layer or corrugated material layer, or any combination of higher density paper or cellulose based products with foamed cellulose or corrugated material . In this particular embodiment, the spacer layer is a layer of foam-formed cellulosic material having a grammage of about 70 ^g /m2.

On the inner side of the spacer layer 11a, the laminate comprises a thin and high-density paper face layer 12a, on which a barrier coating 13a, 14a is applied, the paper face layer thus being in a sandwich structure with the spacer layer 11a and the outer paper face layer 16a interaction. The paper face layer 12a is a thin high density dense surface barrier paper layer with a surface roughness below 300 Bengtsen ml/min. In particular, a greaseproof paper of the SuperPerga WS parchment type from Nordic Paper was used having a grammage of 32 g/m ² and a surface roughness of about 200 ml/min.

The inner side also comprises an innermost heat-sealable thermoplastic layer 15a, which is also a layer of packaging laminate that will be in direct contact with the filled food product in the final packaging container. The innermost heat-sealable polymer layer 15a is applied to the barrier paper face layer 13a by melt extrusion coating or melt coextrusion coating of a multilayer polymer structure onto the inner side of the barrier paper face layer 13a. The barrier paper may be first coated with one or more other barrier coatings. In this embodiment, it is first coated with a PVOH barrier polymer, which was applied to the paper surface layer by means of an aqueous dispersion in a previous coating and drying operation. Subsequently, a metallized coating 14a has been applied over the precoat surface 13a. Alternatively, the barrier coated paper face layer 12a may be directed in the laminate such that the barrier coating 14a faces outward in the packaging laminate, towards the center and spacer layer 11a, but in this particular embodiment it is directed towards Inward, toward the innermost seal. In an alternative embodiment, the paper face layer 13a itself provides some barrier properties when laminated between polymer layers, so that it can be uncoated and still provide some barrier properties and thus be without any further coating barrier layer. Furthermore, the paper face layer 16a in the outer module may be this or a similar oil-repellent barrier paper on which the printing surface is provided by, for example, a thin clay coating or similar white coating.

The (co)extrusion coating of the innermost layer 15a can be done before or after lamination of the inner layer to the spacer layer 11a. Alternatively, the innermost heat-sealable layer or layers 15a may be applied in the form of a preformed film, adding further stability and durability by orienting the film to a higher degree than is achievable in extrusion coating operations. sex. In addition, the inner material layer may be pre-laminated as an internal separate module before laminating the inner material layer to the spacer layer 11c. However, in this particular embodiment, the barrier-coated paper face layers 13a-14a are first laminated to the release layer 11a or the remainder of the laminate, and are then applied on the inside of the barrier-coated paper layer with a Melt extrusion coating of a layer or layers 15a of a heat-sealable polymer which is a polyolefin comprising metallocene catalyzed linear low density polyethylene (m-LLDPE) and low density polyethylene (LDPE) Blends of Low Density Polyethylene Compositions.

On the other side, ie on the outside of the spacer material layer 11a, the packaging material comprises a printed substrate layer of thin high density paper 16a with a grammage of 70 g/ ^m2 and a smooth printed surface. If a white printing base is desired, the tissue paper face layer can be provided with a clay coating or the like. The paper 16a also constitutes the facing layer on the outside of the sandwich structure interacting with the spacer layer 11a. In the final laminate, the substrate 16a is printed and decorated with printed patterns from various colors, images and text. The material on the outside of the main body layer also includes an outermost liquid-tight and transparent plastic layer 17a, preferably a heat-sealable thermoplastic material, such as a polyolefin, such as a layer of polyethylene material. The print substrate and paper face layer 16a may be printed before or after lamination to the spacer layer and the outermost plastic layer 17a is applied to the print substrate layer in a separate operation either before or after lamination to the spacer layer 11a. If the plastic layer 16a is coated with a decorative print before laminating the plastic layer 16a to the spacer layer, the entire outside material is thus produced as a module on the outside of the spacer layer, i.e. as a pre-laminated outside, which It is then laminated to the rest of the spacer layer or laminate. The lamination operation may be a melt extrusion lamination operation whereby an intermediate thermoplastic adhesive layer 18a is applied between the spacer layer and the print substrate and paper face layer 16a. However, in this particular embodiment, the lamination of the print base paper face layer 16a towards the spacer layer 11a is achieved by applying a small amount of an aqueous solution of binder which is partially absorbed into the corresponding cellulose layer and effectively bonds the two paper-fiber layers together. It is performed by bonding the plain layers together, the binder being starch or nano/microfibrillar cellulose or polyvinyl alcohol/polyvinyl acetate or similar hydrophilic substances that readily bind to the cellulose molecules. Of course when the tacky material has inherent barrier properties, such adhesives, albeit applied in very low amounts, can further contribute to the resulting oxygen barrier properties of the laminated packaging material.

The water-based adhesive also facilitates the recycling process, allowing the layers to delaminate from each other more easily than using a hydrophobic polyolefin adhesive layer.

The hardness of the laminated packaging material of this example is 128mN.

In yet a different embodiment, the print substrate 16a may be a polymeric film, such as a color shifting film or a metallized film, having a color and surface suitable for decorating a printed background. If no paper cover is used with the printing substrate, it must have an integrated paper cover in the body layer, on the outside of the spacer layer 11, or the spacer layer must have a higher density and grammage, e.g. as a layer of corrugated material .

In Fig. 1b a similar cross-section of a second embodiment of a laminated packaging material 10b is shown. The laminate is essentially the same material as in Figure la except for the barrier coating of the dense surface barrier paper 12b. The spacer layer 11b is laminated to the barrier paper via an intermediate adhesive 19b. The innermost heat-sealable layer 15b is the same as or similar to 15a in the packaging material 10a.

The spacer layer 11b is made of cellulosic material such as a layer of fibrous cellulosic or corrugated material formed from foam, or any combination of higher density paper or cellulose based products with expanded cellulose or corrugated material to make. In this particular embodiment, the spacer layer is foamed cellulose having a grammage of about 90 ^g /m2.

Inside the spacer layer 11b, the paper surface layer 12b is a dense surface barrier paper layer with a surface roughness less than 300 Butson ml/min. A greaseproof paper of the Super Perga WS parchment type from Nordic Paper was used, 40 g/m ² with a surface roughness of about 200 ml/min. The barrier paper is first coated with a PVOH barrier polymer, which is applied to the paper surface layer by means of an aqueous dispersion coating in a previous coating and drying operation. Subsequently, a PECVD DLC coating 14b has been applied on top of the precoat surface 13b. The DLC coating is applied at a thickness of 5 to 50 nm, for example 10 to 40 nm. The barrier coating 14b is directed inwardly towards the innermost seal layer.

The (co)extrusion coating of the innermost layer 15b can be done before or after lamination of the inner layer to the spacer layer 11b. Alternatively, the innermost heat-sealable layer or layers 15b may be applied in the form of a preformed film, adding some further stabilization by orienting the film to a higher degree than is achieved in extrusion coating operations. and durability. The innermost layer or layer 15b being a heat-sealable polymer material is a low density polyethylene composition comprising a blend of metallocene catalyzed linear low density polyethylene (m-LLDPE) and low density polyethylene (LDPE) .

In addition, the material has excellent oxygen barrier properties and is suitable for forming carton packs for sensitive and/or long-term storage of liquid foods. The material has good integrity resistance to the migration of free fatty acid species present in fruit juices and similar food products, with a bending stiffness of about 340 mN.

Figure 1c shows a cross-section of a third embodiment of a laminated packaging material 10c. The laminated packaging material is in principle the same as that described in Figure 1a, but the innermost heat-sealable layer is laminated to the metallized layer 14c by means of an adhesive polymer containing a compound modified by copolymerization with a monomer having carboxyl functionality. Polyethylene, namely ethylene acrylic acid copolymer EAA. By adding this simple feature of tacky polymers, the adhesion of the inner layer to the metal can be increased to some desired degree, but more importantly, the oxygen barrier properties of this high barrier dense surface paper are within its It can be improved even further when laminated into packaging materials, reaching unexpected levels of enhancement. The inner polymer layer is preferably applied to the metallized layer by co-extruding a multilayer molten curtain of coating layer structure 22c in one simultaneous coating operation. When the spacer layer 11c is a corrugated material of about 100 ^g /m2 and the outer paper face layer is a combination of a tissue paper with a grammage of 70 ^g / ^m2 and a dense surface barrier paper 12c of 40 g/m2, the final laminated packaging material A bending stiffness of about 130 mN is obtained.

Figure 1d shows a cross-section of a third embodiment of a laminated packaging material 1Od. This laminate differs from the laminate described in FIG. same.

As described in laminate 10c, the metallized coating 14d is coextrusion coated with a multilayer structure of an EAA layer 21d closest to the metal surface, with 5-8 ^g /m2 of EAA layer 21d on its other side The polyamide layer 22d is adjacent, and the polyamide layer 22d is further adjacent to the EAA layer 23d. Finally, the multilayer structure has an innermost heat-sealable low density polyethylene composition layer 15d inside the second EAA layer 23d. The innermost layer 15d may be co-extruded with the polyamide and EAA layers, or alternatively coated onto the polyamide extruded layer in another extrusion step. Preferably, the inner layers are all applied in a single coextrusion coating operation in order to minimize the number of lamination roll nips.

In any of the laminated packaging materials according to the invention, the thin high density face paper layer on the outside of the spacer layer may thus have a grammage of 20 to 100 g/m ² , for example 30 to 80 g/m ² , for example 30 to 80 g/m 2 . 60g/m ² , and paper with a density of 600 to 1500kg/m ³ . In a particular embodiment, the paper face layer may also be a greaseproof paper, either alone or coated with an additional barrier coating, such as a metallized coating. Some greaseproof papers, when laminated between plastic layers such as polyethylene laminate layers, provide further gas barrier properties below ² cc/m2/day/atm at 23°C and 50% RH.

In Figure 2a it is schematically shown how one layer or a module of layers is laminated to another layer/module by cold water-based adhesive absorption lamination such that a very small amount of aqueous adhesive solution is applied onto one of the surfaces to be laminated to each other, and then absorb the aqueous adhesive solution into one or both of the surfaces while applying pressure to bond them together. Thus, in an embodiment for making the laminated packaging material in Figures 1a-1d, an aqueous adhesive solution is applied to the surface to be laminated of the outer layer/material module 1B; 2B; 3B; 4B, the outer layer /Material module 1B; 2B; 3B; 4B denotes the layer on the outside of the body and spacer layer, i.e., on the non-printing surface of the printed substrate layer 16a; 16b; 16c; 16d in the adhesive application operation 21 Floor. At the lamination nip between the two rolls, the central module material roll 1A; 2A; 3A; 4A, representing the body layer including the spacer layer, is laminated to the outer module material roll at the lamination station 22 under the following conditions For materials 1B; 2B; 3B; 4B: both webs are conveyed simultaneously through rollers under a pressure high enough to bond the two surfaces together, but not so high that the low-density spacer layers of the sandwich structure collapse Gap. The obtained intermediate pre-laminate rolls of two layers/module 1A+1B; 2A+2B; 3A+3B; 4A+4B are forwarded to another lamination station for lamination to a third module or part thereof, e.g. As will be described hereinafter in Figure 2b, or alternatively rolled onto reels for intermediate storage or transport to a different time or place where final lamination and finishing steps will take place. When laminating the inner material modules 1C; 2C; 3C; 4C to the central layer/module material or pre-laminated central and outer modules, the method of cold water-based adhesive absorption lamination may also or alternatively be applied.

In Fig. 2b is shown schematically how one layer/module can be laminated to another layer/module by melt extrusion lamination such that the two surfaces to be laminated are bonded to each other by an intermediate thermoplastic bonding layer. According to this example, the pre-laminated webs of the two modules laminated in the example of Fig. 2a are conveyed to the lamination nip simultaneously with the webs of the inner material modules 1C; 2C; 3C; 4C. Simultaneously, a molten curtain of thermoplastically bonded polymer 23; 19a; 19b; 19c; 19d is extruded down into the lamination nip and cooled while pressing the two webs together so that the center of the cellulose base Sufficient adhesion is obtained between the surfaces of the modules, ie the spacer layers 11a; 11b; 11c; 11d, and the barrier paper 13a; 13b; 13c; 13d of the inner material modules.

Figure 3a shows an embodiment of a packaging container 30a produced from a packaging laminate 10a; 10b; 10c; 10d according to the invention. Packaging containers are especially suitable for beverages, sauces, soups, etc. Typically, such packages have a volume of about 100 to 1000 ml. It may be of any construction, but is preferably brick-shaped, with longitudinal and transverse seals 31a and 32a respectively, and optionally with opening means 33 . In another embodiment not shown, the packaging container can be shaped as a wedge. To obtain such a "wedge", only the bottom part of the package is folded into shape so that the bottom transverse heat seal is hidden under the triangular flap, which is folded and sealed at the bottom of the package. The top transverse seal remains deployed. In this way, the half-folded packaging container remains easy to handle and dimensionally stable when placed on a grocery store shelf or table or the like.

Figure 3b shows an alternative preferred example of a packaging container 30b produced from an alternative packaging laminate according to the invention. The alternative packaging laminate is thinner by having a thinner cellulose body layer 11, so it is not dimensionally stable enough to form a cube, parallelepiped or wedge shaped packaging container and does not fold into shape after transverse sealing 32b. Therefore, it will remain in the pillow-shaped pouch container and be distributed and sold in this form.

Figure 3c shows a gable top-shaped package 30c formed from a pre-cut sheet or blank folded from a laminated packaging material comprising a paperboard body layer and a durable barrier film of the present invention. Flat top packages can also be made from similar blanks.

Figure 3d shows a bottle package 30d which is the combination of a sleeve 34 formed from a pre-cut blank of the laminated packaging material of the present invention and a top 35 formed by combining injection molded plastic with an opening device such as a screw plug or the like. ) combined to form. This type of packaging is known for example under the trade name Tetra and Tetra Sales. These particular packages are formed by connecting a molded top 35 with an opening device attached in the closed position to a tubular sleeve 34 of laminated packaging material, the resulting bottle-top capsule is sterilized, and the It is filled with food and finally folded - forming the bottom of the package and sealed.

FIG. 4 shows the principle described in the introduction of the present application, ie forming a web of packaging material into a tube 41 by joining the longitudinal edges 42 of the web to each other in a lap joint 43 . The tube 44 is filled with the desired liquid food product and divided into individual packages by the tube's repeated transversal seals 45 at a predetermined distance from each other below the level of the filling content inside the tube. Package 46 is separated by cuts in the transverse seals and is given the desired geometric configuration by being folded along pre-prepared crease lines in the material.

In Fig. 5, it is shown that the oxygen barrier properties of a laminated packaging material from a bulk layer of cellulose corrugated material compared with a reference conventional paperboard-based laminated liquid packaging material when an aluminum foil barrier layer is laminated in the same manner and formed of the same type Deterioration when filling a 1 liter folded bag-shaped package. It has been demonstrated that when aluminum foil is laminated to a corrugated layer and formed into a package, there are a large number of cracks in the aluminum foil and this is believed to be responsible for the loss of oxygen barrier properties. This suggests that when a low-cost cellulose-based spacer layer is chosen, thus changing the mechanical properties of the bulk layer, the oxygen barrier properties are consequently degraded and there is a need to add or improve or replace existing barrier materials.

Reference laminate: //LDPE/80mN cardboard/LDPE/aluminum foil 6μm/EAA/blend LDPE+mLLDPE/

Example 1: //LDPE/200g/m ² corrugated paper/LDPE/aluminum foil 6μm/EAA/blend LDPE+mLLDPE/

In Figure 6, it is shown that the OTR of the metallized layer/coating can be further improved in combination with extrusion coating/lamination of the metallized barrier layer onto an adhesive polymer such as EAA. Such effects of course come in handy when the barrier properties of metallized materials need to be improved. The specific experiment behind this conclusion was carried out by coating a 50 g/m2 thin dual phase paper with ^two layers of 1 g/m2 PVOH and subsequently applying a metallized coating on top of the PVOH with an OD of about 2 (Optical density). When such a barrier coated paper is laminated to the laminate and laminated to the adjacent layer of the LDPE laminate and the blend of LDPE and metallocene-LLDPE on the inner side, at 23°C and 50% The RH oxygen transmission rate becomes almost as high as 10 cc/m ² , 24 hours, 1 atm. When laminated in the same way, the metallization layer adhered to the adjacent layer of EAA, thus further bonding to the LDPE-m-LLDPE blend, the oxygen transmission rate was surprisingly reduced to ^4cc /m2 down to 40%.

Laminated structure:

/LDPE/paper 50g/m ² /LDPE/paper 50g/m ² with 2×1g/m ² PVOH-metallization/EAA/LDPE+mLLDPE/

In Figure 7 it is shown that a dense surface barrier paper layer can provide photoresistive properties when metallised with a nano-thin aluminum layer. Thus, a graph is shown of the light transmittance of light of different wavelengths for a barrier paper comprising a non ^- metallized dense surface, as tested above, i.e. having an Surface roughness for laminates of Super Perga WS parchment. Correspondingly similar laminated samples (with the only difference that the barrier paper is also metallized) transmit almost no light in the tested wavelength range (including visible light). The dense surface of the barrier paper thus also increases the density and quality of the metallization layer. It was also concluded that a metal layer with an optical density of about 2-3 OD would also provide improved heat sealing properties by induction heating, which also means a higher quality coating. Accordingly, further important advantages are obtained by laminates comprising the metallized dense surface barrier papers of the invention.

Figure 8 shows how the flexural stiffness of a laminated packaging material increases with the incorporation of at least one paper facing layer on one side of a low stiffness body paperboard or low density cellulose based spacer layer. Such a paper top layer can thus improve the stiffness of the laminate and thus also support the barrier properties of the material in a better manner.

The laminated samples tested for bending stiffness were:

1: 80mN cardboard for smaller packages

2:1 paperboard, laminated with 6.3μm thick aluminum foil

3:1 paperboard laminated with 40g/ ^m2 Super Perga WS parchment

⁴ : 165g/m2 main layer of corrugated paper material, one side is laminated with 72g/ ^m2 paper, and the other side is laminated with 6.3μm thick aluminum foil

⁵ : 165g/m2 main layer of corrugated paper, one side laminated with 72g/ ^m2 paper, and the other side laminated with 40g/ ^m2 Super Perga WS parchment paper.

It can thus be seen that a low cost and low grade body layer may more suitably be supported by a paper face layer on at least one side, and it is preferred to have such a paper face layer on each side of the body layer. The bending stiffness of the samples was measured by Lorentzen & Wettre according to ISO2493-1.

We have accordingly seen that the new laminated packaging material of the present invention is also capable of providing packaging containers with good integrity under wet conditions, ie can be used for packaging liquid or moist food products with a long shelf life.

Typically, the grammage mentioned above and in the description below is measured by SCAN P 6:75. Material density and layer thickness are measured according to ISO 534:1988.

experiment:

A dense surface (CS) barrier paper of the type from Nordic Paper (known as SuperPergaWS parchment) 32 ^g /m ply was synthesized into the following structure with or without the application of various barrier coatings:

//Outside 12g/m ² LDPE/Duplex CLC 260mN/20g/m ² LDPE/Barrier paper/20g/m ² /Inside heat seal: 20g/m ² blend of LDPE and m-LLDPE//

Duplex CLC paperboard is a conventional type of clay coated paperboard and m-LLDPE is a metallocene catalyzed linear low density polyethylene. The barrier paper is thus laminated between layers of thermoplastic polymer, ie polyethylene.

CS shielding paper was laminated, 1) uncoated, 2) metallized directly onto the cellulose paper surface, 3) pre-coated with 1 g/ ^m2 of PVOH followed by metallization onto the PVOH surface, 4 ) pre-coated with 1 g/m ² of EAA followed by metallization coating, and in the final experiment, 5) pre-coated with 1 g/m ² of PVOH followed by PECVD coating with DLC barrier coating. The metallized coating was applied to an optical density of 2.5. The DLC coating is applied at 5-50 nm (eg 10-40 nm).

It can be seen from the results of the oxygen transmission rate measurements performed with the Oxtran device at 23°C and 50 and 80% RH respectively, the device is based on a coulometric sensor, and the standard deviation of the results is ±0.5 cm ³ /m ² /day. Surprisingly, PVOH and metallized coated barrier papers have equivalent oxygen barrier properties to aluminum foil, i.e. less than 1 cc/ ^m2 /24h/atm at 23°C and 80% RH, eg about 0.5cc/ ^m2 /24h/atm or lower. In addition, PVOH-metallized coated barrier papers had the best water vapor transmission rate and were in line with the requirements to achieve the same performance as aluminum foil packaging. The water vapor transmission rate, in g/m ² , was measured at 40°C and 90% RH for 24 hours.

It can be seen that the metallization of the uncoated barrier paper does not further enhance the oxygen barrier properties, but on the other hand does not reduce any oxygen barrier properties either. Furthermore, it can be seen that the precoat of EAA does not contribute to the oxygen barrier properties of the laminates, whereas the PVOH precoat interacts with the adjacent layers in a positive manner to improve the oxygen barrier properties.

Coating combinations of PVOH and PECVD-applied DLC (diamond-like carbon) coatings also provide very good oxygen barrier properties and good water vapor barrier properties, but the latter leaves some small barriers up to aluminum foil levels. room for improvement.

From forming a heat-sealed enclosure, simulating the reformation and sealing of the laminated packaging material into a bag, it was further seen that the material most able to withstand such treatment was preferably a PVOH coated and metallized coated dense surface barrier paper. Such good oxygen barrier properties have never been seen before. As shown in Table 1, the barrier paper also provided some barrier properties when laminated (uncoated) into the laminate structure, which was not degraded by the metallization operation and/or subsequent heat sealing of the enclosure. This means that oxygen enters the package only through its planar surface, its oxygen barrier properties are unaffected by metallization operations and unaffected by folding operations.

A reference heat-sealed enclosure made of conventional aluminum foil and paperboard laminate resulted in an OTR value of 0.024cc/pack/day/0.2atm at 23°C, 50% RH.

Table 1

Early attempts to increase the OTR of similar high density papers with PVOH precoats have shown that subsequent metallized coatings increase the oxygen transmission rate, rather than decrease it.

Many different barrier papers were considered and studied over time in order to find the best working dense surface barrier paper layer for the present invention. It has been concluded that the paper should have a grammage of 60 g/m ² or less, a thickness of 60 μm or less, and a density of 800 kg/m ³ or higher. Preferably, the paper should have a grammage of 20 to 40 g/m ² and a thickness of 20 to 40 μm. These properties are important for providing the correct mix of mechanical properties, for lamination into packaging material structures, and for enabling cost-effective vapor deposition of barrier coatings. Furthermore, it has been seen that the surface of the barrier paper should have a density below 450 ml/min and a smooth topography, such as below 300 ml/min, such as below 250 ml/min, such as density and smooth topography below 200 ml/min, as it seems to have an effect on the final barrier properties of the coated material. The superior oxygen barrier and water vapor barrier properties of PVOH precoated and metallized dense surface barrier papers as defined above are very surprising and it is believed that this aspect is a synergistic interaction between the paper type and its mechanical and surface qualities , and on the other hand the result of the combination of precoating and metallization materials and possible optimum layer thicknesses. When employing higher thicknesses or amounts of PVOH and metallization respectively, it has been seen that the barrier layer effect does not increase much beyond a certain thickness, and thicker coating layers become more brittle and susceptible to cracking.

Filled and sealed packaging container Tetra Aseptic 1000ml produced from material on Variant 21 (Variant 21) exhibits an excellent oxygen barrier of not more than 0.06cc/package/24 hours, which is completely comparable to the same package made from a packaging laminate based on an aluminum foil barrier quite. This has also never been seen when working with barrier materials on paper substrates.

In Table 2, the induction heating performance of various metallization-coated laminate samples is compared and it can be seen that, also in this respect, the PVOH-coated and subsequently metallized specific CS barrier papers of the present invention are also Is optimized beyond what has been seen from other similar high density papers. For a better function of inductively heating adjacent polymer layers, with the help of metallization layers, the SR value (sheet resistance) should be as low as possible at a reasonable optical density of the applied metallization layer and be able to operate over a wide range of power Provides heat sealing of thermoplastic polymers at a setting that is able to provide a good heat seal quickly and reliably in a robust sealing operation.

The evaluation of the different samples was scored on a scale of 1-3, where 1 means "unacceptable", 2 means "not sure", and 3 means "acceptable".

The laminate samples tested were: (g/m ² ) metal layer towards the inside i.e. LDPE+mLLDPE

Variant 2: //LDPE12/80mN cardboard/LDPE20/Super Perga 32 metallized to OD1.3/LDPE+mLLDPE25//

Variant 3: //LDPE 12/80mN cardboard/LDPE 20/Super Perga 32 metallized to OD1.6/LDPE+mLLDPE 25//

Variant 8: //LDPE 12/30mN cardboard/LDPE20/Super Perga32 metallized to OD1.3/LDPE+mLLDPE25//

Variant 9: //LDPE 12/30mN cardboard/LDPE 20/Super Perga32 metallized to OD1.6/LDPE+mLLDPE25//

Variant 21: //LDPE12/260mN cardboard/LDPE20/Super Perga32+PVOH1+metallized to OD 3/LDPE+mLLDPE 25//

Table 2

From the above experiments it can be concluded that the metallized precoated dense surface barrier papers of the present invention also show great potential for robust and repeatable induction heat sealing at reasonable optical densities of the metallized coating. For good sensing performance, an OD of at least 2.5 is sufficient. As a rule of thumb, differences in paperboard quality and the thickness of the innermost heat-sealing polymer layer do not significantly affect the sealing effect. A precoat under the metallized coating has proven to be necessary for a robust sealing result and should be chosen to be sufficiently thermally stable and resistant to melting or degradation under the influence of induction heating, for example, PVOH.

The invention is not limited to the embodiments shown and described above but may be varied within the scope of the claims. As a general remark, the ratios between the thicknesses of the layers, the distances between the layers and the dimensions of other features and their relative dimensions compared to each other should not be considered as shown in the drawings, which merely show the relative The order and type of layers, and all other features are to be understood as described in the specification.

Claims (19)

1. laminate fabric element base fluid state or semi-fluid food packaging material (10a for being heat sealed into sterile packaging container；10b； 10c；10d) comprising paper, cardboard or other cellulosic-based material material of main part layer (11a；11b；11c；11d), most interior can Heat-sealing and liquid-tight thermoplastic polymer layer (15a；15b；15c；15d), the most interior polymeric layer by with packaging food It is in direct contact, the barrier layer (12-13-14 (a being laminated between the body layer and the innermost layer；b；c；D)), wherein it is described Barrier layer is compact surfaces barrier paper (12a；12b；12c；12d), with 800kg/m³Or higher density, it is less than 450ml/ The Bendtsen smooth surfaces angle value (ISO 8791-2) of minute, 60 μm or lower thickness, 60g/m²Or lower grammes per square metre.

2. laminated packaging material according to claim 1, wherein compact surfaces barrier paper has 20 to 40 μm of thickness Degree and 20 to 40g/m²Grammes per square metre, such as 25 to 35g/m²Grammes per square metre.

3. laminated packaging material according to any one of the preceding claims, wherein compact surfaces barrier paper has 300ml/min or lower Bendtsen smooth surface angle value, such as 250ml/min or lower, such as 200ml/min or lower Bendtsen smooth surface angle value.

4. laminated packaging material according to any one of the preceding claims, wherein compact surfaces barrier paper material tool There are the tensile strength of 40 to 80MPa horizontal direction, such as 50 to 70MPa, such as the stretching of 55 to 65MPa horizontal direction is strong Degree, the tensile strength of the machine direction of horizontal direction, that is, CD and 140 to 180MPa, such as 150 to 170MPa, such as 155 to The tensile strength of the machine direction of 165MPa, machine direction, that is, MD.

5. laminated packaging material according to any one of the preceding claims, wherein compact surfaces barrier paper material tool There is 0.4 to 0.6kN/m wet strength (ISO3781).

6. laminated packaging material according to any one of the preceding claims, wherein compact surfaces barrier paper material tool Have the air permeability less than 2.0nm/Pas, such as less than 1.8nm/Pas, such as 1.7nm/Pas and hereinafter, for example from 0.1 to The air permeability (SCAN P26) of 1.7nm/Pas.

7. laminated packaging material according to any one of the preceding claims, wherein compact surfaces barrier paper material tool There is the tear resistance (ISO 1974) less than 200mN on MD and CD.

8. laminated packaging material according to any one of the preceding claims, wherein the most interior heat salable layer is described Thermoplastic polymer is polyolefin, such as polyethylene, such as the linear low density polyethylene (m-LLDPE) of metallocene catalysis and low The blend of density polyethylene (LDPE).

9. laminated packaging material according to any one of the preceding claims, wherein compact surfaces barrier paper passes through heat Thermoplastic polymer binder course (19a, 19b；19c；19d) it is laminated to the body layer, the thermoplastic polymer such as polyolefin, Such as polyethylene, such as low density polyethylene (LDPE) (LDPE).

10. laminated packaging material according to any one of the preceding claims, wherein compact surfaces barrier paper is applied It is covered with vapor deposition barrier coat, such as aluminum metallization coating.

11. laminated packaging material according to any one of the preceding claims, wherein compact surfaces barrier paper is applied It is covered with precoating material (13a；13b；13c；Then coat 13d) and further vapor deposition barrier coat (14a；14b； 14c；14d) on the surface of the precoating.

12. laminated packaging material according to any one of the preceding claims, wherein the precoating material be selected from by Polyvinyl alcohol (PVOH), ethylene-vinyl alcohol (EVOH), starch and starch derivatives, cellulose and cellulose derivative, such as receive Rice/micrometer fibers shape cellulose and nanocrystal cellulose and other polysaccharide and polysaccharide derivates, polyvinylidene chloride (PVDC) and polyamide composition group barrier material.

13. laminated packaging material according to any one of the preceding claims, wherein the precoating barrier material is PVOH, and the vapour deposition coating is that optical density is higher than 1.5, such as higher than 1.8, such as higher than 2, such as from 2 to 3 gold Categoryization coating.

14. laminated packaging material according to any one of the preceding claims, wherein the body layer includes being used as in institute The cellulose material of the wall in the sandwich in laminated packaging material is stated, the density of the wall is less than 750kg/ m³, such as less than 700kg/m³。

15. laminated packaging material according to any one of the preceding claims, wherein the wall is by foam shape At fibrous layer made of technique, have 100 to 600kg/m³Density, such as 200 to 500kg/m³, such as 300 to 400kg/ m³Density.

16. liquid or semi-fluid food packing container (30a；30b；30c；30d), it includes any one of such as preceding claims The laminated packaging material.

17. manufacturing laminate fabric element base fluid state or the method for semi-fluid food packaging material comprising following steps：

A) compact surfaces barrier paper is laminated on body layer；

B) most interior heat sealable thermoplastic polymer layer is applied to the other side that the compact surfaces obstruct paper, and

C) the other layer including printed substrate layer with printed decoration pattern is applied to the another of the body layer Outside.

18. the method for manufacture laminate fabric element base fluid state according to claim 17 or semi-fluid food packaging material, Described in compact surfaces barrier paper pass through apply 0.5 to 4g/m²Aqueous adhesive composition (21) and then by the paper It is bonded to each other (22) with the body layer and is laminated on material of main part layer.

19. the manufacture laminate fabric element base semi liquid state according to any one of claim 17-18 or viscous food packing timber The method of material, wherein in addition the printed substrate layer on the outside of the material of main part layer is used as the layer of the face in sandwich Paper, the other paper have density be higher than 600kg/m³Density and 70g/m²Or lower grammes per square metre, with the material of main part The wall of layer and the compact surfaces on the opposite side of the wall and the material of main part layer obstruct paper phase Interaction.